I will use disabled bays in Tesco if it is late (majority will be free) as I have difficulty in walking but haven’t got through the lengthy and quite arduous assessment processes for PiP and a Blue Badge. This means I can get to the first food aisle before my knee gives out. I wouldn’t do it in daytime because the chances are I am likely to obstruct someone with a registered need.
You can use disabled spaces in car parks as you don’t need a blue badge to use one. Anyone classed as disabled can use them if it meets their needs. If you really don’t want to use them then use parent and child ones. in tescos these seem to be the closest and more of them.
Whilst understanding what you are saying, this approach is not without risk. Parking in a disabled space without displaying a blue badge can result in a Parking Charge Notice. Whilst these are not legally enforceable as they are issued on private land, they can require quite a bit of effort to over turn them, unless you are prepared to just ignore them and receive several threatening letters, which isn’t for everyone. My late father received one even though he is a blue badge holder because he forgot to display the blue badge. He got it overturned but it caused him some anxiety and hassle to do so. Personally, if someone has a genuine need to use a disabled space I think it is far more sensible to apply for a blue badge than just feel that they are ‘exercising their rights.’
Just as those of us who have to use disabled spaces can be quite precious about people without blue badges using them, I have found the same with parent & child spaces. Because we need the extra space to bring a wheelchair alongside, I have used them a few times when all the disabled spaces were full and on two occasions I have been challenged by people with children. Whilst this hasn’t stopped me and I’m able to look after myself, I have always been a bit wary about coming back to the car and finding that it has been keyed!