long
@frost Unfortunately, with a seat on a bus or train, you can easily yield the seat to someone more obviously in need of it - unfortunately someone less obviously disabled might need to step up and ask. But with a parking space, who knows how long the person's sitting on it and you can't easily get in touch with them.
My parents (Mom's mobility is completely terrible, my Dad will occasionally use the placard because he feels old and creaky) are REALLY good at spotting people without placards using the handicapped spaces, I wish they didn't do that.