Parking in Morocco is almost like a game. Most people park where they like but parking attendants patrol many streets in the big cities looking out for cars they can ticket. There's no hard and fast rule as to why you'll be targeted so try to park where there is little room for misinterpretation of the situation.
There are few places that you have to pay for parking and they're generally in the cities. Parking costs are very low but you'll have the security of knowing an attendant will be near your car whilst you're away from it.
The parking attendants have the authority to ticket 'illegally' parked vehicles and eventually have them towed away. Police will occasionally get involved if they see a car parked which causes an obstruction.
There are no special dispensations for disabled drivers but if you need a spot with easier access, choose an attendant controlled parking area and ask for assistance – for a few coins, it's usually willingly given.