I think the actual situation is probably incredibly complicated, personally I think lazy parents are probably only a really, really tiny proportion of the problem.
My personal experience was my older child potty trained prior to 2 1/2 with very little bother. We had a bit of a regression around 3, but powered through that and never really had problems after that apart from the very occasional accident.
My younger child was a different experience altogether - as far as I am aware he is NT although he is still only 5 and does get very anxious about lots of things, so who knows really.
I tried potty training him a couple of times between 2 and 3 and it was awful. Not awful as in loads of accidents but he was just so anxious and worked up, he refused to even go near a potty or toilet, he was hysterical if he had an accident and was completely miserable and constantly worried for the few days we persisted.
Eventually we managed to get him out of nappies about 3 years 3 months but only with an incredibly slow and steady approach (sitting on potty with trousers on watching TV for a few weeks. Sitting on potty with trousers down but no mention of weeing for a few more weeks. Moving very gradually towards removing nappies until he finally started weeing in the potty). But even after we stopped using nappies we had months of issues - he was terrified of public toilets so we had to carry his potty everywhere for about 6 months even after he was far too big for it, he wouldn't use the toilet at nursery for a little while and then only with a very familiar staff member, even at home I always had to go with him for company. And any time he was nervous he would just hold in his wee for hours until he was in pain. I would say we finally cracked it and overcame all these issues and anxieties 8 months after we removed nappies and about 6 weeks before he started school.
So we did it just in time but it was very hard work - certainly I never felt lazy. Would I have had the patience to continue if I had poor mental health myself? Probably not. Would I have been able to continue if I was at crisis point trying to make my money stretch to feed my family? Probably not. What about if I had my own health problems? Probably not.
I just think a bit more empathy for other families and the poor little children at the heart of this is needed. Perhaps we should be targeting the anger at all the government cuts to pretty much everything and the cost of living driving families to desperate places, not parents who are on the whole just doing their best.