Best advice I would give to the average Joe Blogs on this site is DON’T challenge people misusing Disabled Parking spaces/bays, unless you have the authority to do so.
So very good points made above for not doing so, and furthermore you don’t know how people are going to react nowadays.
Somebody may have severe anger problems or mental health issues, and your challenge may be that trigger which could start something you’d wish you hadn’t started.
You don’t know what people are capable of these days. And, whilst I’m not suggesting we live in fear of one another, I’m merely saying that the extra 5 seconds added to your walk from your car to the the store isn’t really worth the aggrevation.
I have seen people go toe to toe with someone who challenged them, even though there was at least 30 years of age difference between them. Sometimes people don’t care about consequences.
I just have the mindset of “Why let something like that bother me” when there’s a lot more serious things happening in the world right now.