Yes, it is!

I haven't been to Europe yet, but the few times I've ridden on a ferry, they weren't large enough to accommodate any cars. The one island we ended up on from the mainland did have some cars, but they were owned by the people who lived there. The tourists or visitors were getting around on foot, bike or a moped type of motorized vehicle. Some streets you couldn't really drive down anyway.

I don't know. It seems to me that in many cases the idea of island living is to get away from it all, not bring it with you. The size of the island is going to dictate if vehicles are a part of that living or not, but the few I've been to have some form of transportation, if not buses or some other kinds of public transit.