To still be shocked by what I saw!!

Well done OP. Like others have said, it takes a village, and we all should be looking out for children in danger and intervening when we can.
I once saw a couple get into their car at the supermarket (full weekly shop) and drive away with their baby (no older than 6 months) on the lap of the passenger in the back seat (no car seat visible). I rang 101 with the details including car make, model, colour and reg, plus description of the driver. The operator thanked me for reporting and suggested that it would have been completely reasonable to have called 999 as there was an immediate risk to life for the child.

Without doubt you were correct to report this.

I’m sure that was horrible

Sometimes you do things based on what’s a best fit for the circumstances. To give an admittedly extreme example, we were caught in this on our way back from holidaying in the Lake District when DS was around 20 months old. There were no warnings and it was lucky in a way we were coming back from holiday as had toys, games, food and a water bottle but in the end I did have to take him out because he was becoming beside himself (I knew how he felt)

The traffic inched forward: I think we were stuck for over six hours. Obviously that’s a fairly extreme situation but it does happen.

And it is true actually that it is permissible in taxis and buses so it isn’t always a case of absolutes. Common sense responds to situations individually and I don’t think there’s always a hard rule or way of doing things.

You did exactly the right thing OP.

They say it takes a village to raise a child - and some parents simply don’t have the intelligence to understand why some things they do are wrong - both morally and illegally, therefore it is up to the ‘village’ to help. I’d like to hope the police will speak to the driver and passenger and make them understand why not using a car seat is illegal and unacceptable (except in an emergency).

In my area a driver was caught going the wrong way down the motorway with 5 adults and 4 unrestrained children in the car

My neighbour did this with their 18 month old who was crying in the car. Sudden stop and the baby went through the windscreen and died instantly.

The mother was like a walking ghost even several years later. Drank heavily and could not cope with the guilt.

Please don't risk it.

Well i wouldn’t do it in a taxi, I’d either use a car seat or at the worst sit in the back not the front. With a bus again you are further back from the windscreen and every baby I see on a bus is strapped in a pram.

Well done for reporting it. Idk if police would follow up, but at least your conscience is clear and you did the right thing.

You can do this in taxis and on buses so it isn’t exactly shocking.

Absolutely ridiculous busybody move. I hope you also reported yourself for taking your eyes off the road to take in as much detail as possible.

No room.

@CormorantStrikesBack in all honesty no. Which I recognise as quite cavalier in many ways but a lot of ifs - if an accident (which neither DH nor I have had in over twenty five years driving: of course there is always a first time) if we went through a window.

When a baby is that hysterical you take them out and calm down then out then in again and they just start screaming again. I think I did it three times with DS in total and twice with DD, it’s not a weekly occurrence but I’ll hold my hand up and admit to having done it; mea culpa.

I am certainly not saying anyone should do it or that it’s recommended but preferable to me to ignoring a child’s distress and I know not really but that’s how it feels. So the point is the couple may well have had a car seat.

Why on earth would you do this? Wherever you were going, whatever you were doing, it couldn't possibly have been more important than your child's life! Why not just stop the car and get in the backseat so that you could be next to the baby to settle them.

I saw a toddler on the father’s knee the other day. If the airbag went off the kid would be dead.

Were you not concerned with how dangerous that was and if there’d been an accident your baby would probably have gone through the windscreen? What could be more important than your child’s safety? By all means stop if you need to calm them down, or you sit in the backseat with them still safely strapped in beside you? Lots of options rather than something so dangerous?

Worst I've done is unstrap myself and stick my boob into the rear facing carseat to settle a screaming baby.
Other than that, settling the screams is sometimes just not worth it. There are worse screams that I'd rather not risk hearing

DH driving, me holding a baby on my lap.

One of the many, many things wrong with this country is too many people with this 'none of your business', 'not my problem' attitude. How do you know that child wasn't potentially minutes away from flying into the windshield and suffering serious injury? Even if the person driving was a good driver there are so many angry, impatient, reckless people on the roads you have no control over that it WAS dangerous for the child.

I saw a video on a particular social media platform last night of two guys in a car filming a van in front of them, driver was clearly pissed out of his tree, spinning the van at every corner, swerving into oncoming traffic, going up side banking. Did they call to report it? Nah, filmed it laughing saying he was going to end up killing someone. 'Not my problem'.

Well done for reporting it OP.

Surely you pulled over and stopped while settling them? Or did you drive round with them unsecured in a moving car?

Of course it’s illegal. Driver would be fined and points on their licence if the police caught them so they would be interested.

I’ve done this occasionally with both children as babies when they’ve been absolutely hysterical in their car seats.

You're not wrong to be concerned, disgusted etc but I'm not sure why you are shocked. It happens all the time, have you never seen people driving dangerously before? But good on you for reporting it of course, I hope mothing bad happened.
You'd really be shocked if you went to India. Entire families plus the family dog and a couple of chickens ride a single moped over there. I'm not exaggerating. Such a culture shock and then you come back to the UK and (rightly) carefully strap your child into a properly installed car seat.
Perhaps this couple weren't local and weren't use to the safety rules here.

I'm with you OP. I'd be shocked. But on a daily basis I see things that amount to tremendous stupidity and have to remind myself that some people are totally clueless.

You were absolutely right to report OP.

I can't believe the replies telling you to mind your own business! We all have a duty of care to children in our society. And trying to prevent a child from flying through a windscreen, head first onto a road is the right thing to do. Yeah you couldn't stop them from being idiots right there and then, but hopefully the police caught them, had a word and it will put them off in future.