During certain hours while parked in a residential area.
> Isn't that the point of a vehicle like that?
Vehicular camping is the point of an RV, sure. OTOH, overnight camping isn't the point of a residential parking space.
> During certain hours while parked in a residential area.
The hours you are talking about are night hours.
They have some overlap, but night hours generally begin before 9pm and end before 6am. But, in any case, it is possible to sleep during non-night hours. It may be less desirable, but banning sleeping in vehicles in residential parking spaces in night hours is different than banning sleeping in vehicles in residential areas which in turn is different than banning sleeping in vehicles.
That doesn't make the law equivalent to a blanket ban on vehicular camping, or even a blanket ban on such camping in residential areas.