By 'incarcerated in an institution' are you referring to the detaining of certain categories of mentally unwell or mentally disabled people in a safe and appropriate environment where their needs are more able to be met and they are not a risk to themselves or others by being at large in the community without adequate support or care?
What about when parents are no longer able to manage their adult child's significant needs at home because they are too violent or unpredictable? If so, then I believe that lots of people still are 'incarcerated in institutions' although nowhere near as many as probably should be. And they probably get more access to the outside world these days, with (one would hope) adequate supervision in place. Although that clearly failed the poor child thrown into a crocodile enclosure this week. Goodness knows what that man's TWO carers were doing, but their attention must have been elsewhere. Either that, or he was simply not fit to be outside even with two carers, because he was too unpredictable and could not have been overpowered by them.
I know a learning disabled man in his 20s who has two female carers who take him around our town for the day, one day a week. In general he is happy and well behaved although he does shout out sexually inappropriate things, including comments directed to me. I have not felt threatened, but someone younger or less confident might.
He comes into my place of work because he likes it there and he ALWAYS asks to use our loo. It's not a public loo but we let him. He must be accompanied by BOTH carers at all times. Presumably because they are women it's not deemed safe for either of them to be left alone with him, so they both take him to our bathroom and they both stand outside and wait. If he were to suddenly decide to do something massively inappropriate to them or me, or any member of the public (especially sexually, as he doesn't seem to have any boundaries or filters) it's hard to see what either of them could do to stop him. And yet he's out and about in spite of that.
It's not the done thing to 'incarcerate people in institutions' except in extremis these days, is it? Although what seems to count as in extremis now is anyone's guess given the number of incidences like the crocodile enclosure that we hear about. Yet each time we are told it's a tragic, unavoidable 'one off' act that no-one could have foreseen and we can never completely protect ourselves against mentally unwell or mentally disabled individuals who commit 'freak' acts, out of the blue. Lessons will be learnt yada yada, enquiries will be had, yadda yadda. Well let's be clear, we absolutely could have, and should have protected ourselves from many of these things, but that would have involved 'incarcerating people in institutions' wouldn't it?
I can (without needing to try very hard) think of quite a few people, including many children in very recent times, who would be alive and/or unharmed today, if only certain individuals well known to have 'issues' of one sort or other had been 'incarcerated in institutions' instead out on the streets with no supervision, or inadequate supervision like the incident this week. How often have we heard autism or mental illness cited as a mitigating factor in some of the most harrowing court cases over the last few years?
It seems unlikely the OP's DD would have been 'incarcerated' because her autism doesn't sound profound enough from what we've been told. But we have no idea what she's really like. Clearly Jonty Bravery should NEVER have been out wandering the streets alone. Neither should Valdo Calocane or Axel Rudakabana or many others I don't have the time or energy to google now, to jog my memory for their names. But we all remember the news stories where there have been massive failings due to the sometimes misguided 'compassionate' and 'inclusive' way we do things these days.
Where autism has been a significant factor, the degree of autism itself may not have been a good reason to 'incarcerate' that person, but all of the signs (well known to the families and the agencies dealing with them before their awful crimes) that their autism was causing them to develop unhealthy and violent obsessions most certainly should have been a reason.
Back to the OP's DD. In fairly recent history the OP's DD might well have had her baby adopted at birth because she's unmarried and unemployed and therefore could not have supported her child before the welfare state started to pick up the tab, often for multiple children but no change of personal circumstances, with no questions asked, no judgements made.
Many children who have grown up in dysfunctional and inadequate home environments in the last 40 years or so would probably have had much better outcomes had they been born a few decades earlier and therefore almost certainly been adopted as very young babies.
That is not to say that that applies to every child removed from its mother purely on account of her tender age and marital status, of course. But lots of very inadequate parents are keeping their children now, when in previous times they would not have.
These days the bar for removing a baby for adoption is extremely high and age and marital status obviously don't come into it. Sadly however, neither do many other factors which probably should. Too much thought is given to the rights of the mother and the supposed 'benefits' to the child of keeping contact with her while it rattles around the care system for years and years, waiting for the woman to show signs of pulling herself together. It sometimes happens, but usually doesn't.
In the intervening years, irreparable damage is done to the emotional wellbeing of that child and if they ever are adopted, it's too late. That damage cannot ever be undone.
'Give me the boy until he is seven and I will show you the man.'
They older they are the harder it is, and some adoptions fail, or limp along with massive challenges that traumatise the children and the parents. All in the misguided belief that it was 'better for the child' to stay with its mother, until it became patently obvious that it wasn't. While it might have been better, back in the day when the only reason for removing a baby was the mother's age and marital status, that certainly is not the case now. It's obvious to me which are the situations where those children should be given the chance of a stable, happy and trauma-free life with an adoptive family while they are still no more than weeks old. It nips dysfunctional cycles in the bud instead of allowing them to perpetuate, which I find unforgivable.
So if the bar for removing a baby from its mother for adoption is extremely high these days, it follows that the bar for leaving a baby with deeply inadequate parents is extremely low. That ultimately damages the child, whether it's left with parents who cannot and will not change, or put into the care system from birth but not immediately adopted.
After that essay and circling back to my original point, wouldn't giving these vulnerable, high risk women a BC implant until they can demonstrate (with the right support and education) that they can cope with motherhood just save an enormous amount of grief for everybody?