It’s not. Trikes are 99% of the time ridden by people who used to ride motorcycles but are medically incapable (handicapped) or too old to balance on a bike (and also probably handicapped.)
Assuming this person is actually one of the above, they’re trying to reduce the amount of space their vehicle takes up by not parking dead center in the handicapped spot with a vehicle that doesn’t need the space, thus freeing it up for someone else who also needs it.
The reason people are angry is because the cross hatched zones are intended as spacers to allow people with wheelchairs to access their vehicles via loading ramp. The thing is, not all handicapped people use wheelchairs (crazy, it’s possible to be handicapped in some other way) and even if they do, they could just reverse in to use the OTHER SIDE that’s not blocked.
The trike rider is intending to be courteous by not taking up a whole parking space when they only need a third of it, thus saving the spot for someone who is handicapped and driving a car.
Not good enough for Lemmy! They want him to park dead center so that no one can use the spot! Fucking morons.