Car park lot is usually shared between adjacent space.

the presence of motorbike may cause scratch/dents to the vehicle park beside that lot.
motorbike usually dont give a shit to the car when squeeze in between or blatantly position nearby to the next parking lot.

if you have no vehicle parked there, you may park directly middle of your space.
but for every 1 person that park mid of the parking lot, there are also 10 that may park both car and bike there.

Maybe you need to find out the ratio of good vs bad biker.

perhaps for every 1 good bike that parks nicely in the middle, there could be 10 that park at the border line or cause dents/scratches to the next adjacent vehicle.