Well, I regard the blue badges with a little scepticism. When my mother was dying, it took so long for the blue badge to arrive that she wasn't well enough to be taken out when we got it. On the other hand, there have been rumours of a widespread misuse/ fraudulent obtaining of blue badges. ( this was a few years ago and it is conceivable that abuses may have been tightened up). I remember an acquainatance, who was a doctor, getting a ticket for parking wrongly in the mid 90s and commenting that she would have to get her father, a GP, to sort her a badge, for example. I don't know whether she went through with that.
2 or 3 years later, a co-worker of mine who had a blue badge turned out to have a similar condition to me. I would not have thought it merited a blue badge, and still don't. Neck pain, of an intermittently problematic variety. It was causing me more difficulty than it was her, at that stage; she noticed that I was holding my neck awkwardly and had the grace to blush about the blue badge. She was regularly using a disabled space at work, for convenience, but didn't have any symptoms at that time. I was polite, what else.
I am sure that most people who use the blue badge system do so deservedly, but it is likely that some do not. That's life. I would not choose to park in a disabled space nonetheless out of principle firstly and respect for legal niceties secondly .
As regards parent and child spaces, I would personally appreciate it, likewise,
if they are left for parents and children to use. I find them very convenient, since I have a dashing-off-type toddler, am pregnant and have had poor health in the past year (not neck pain this time). I find it very helpful on the occasions when I use the supermarket to have the extra space and it certainly would be a consideration in choosing where to shop, if I am choosing not to shop online. I think that most people who bag these spaces and are childless are not disabled but are chancers who fancy a convenient parking space and sod everyone else.
I do largely sympathise with the OP. I am sorry she has taken such a bashing and that there has been so much meanness on this thread.