The necessity to own a car in Los Cabos and La Paz depends on what you want to do here. There are people who come to La Ventana, where I live (about 40 minutes by car south of La Paz), and rent a place on the beach, so they don’t need car because all they are going to do is get up and go out on the water and everything is close by. But if they want to go to La Paz, they are going to need a car or they could take the bus, which leaves here at 7 AM and comes back from La Paz at 2 PM. There is also the La Ventana View, in which you can check for posts to see who is going to La Paz. A lot of people do give rides.
If you are in place like La Ventana, then it’s going to extremely inconvenient for you not to have a car if you want to do almost anything except just go to the beach and come back to your house. In La Paz, it’s not going to be a problem. You can get by without a car in La Paz. There are a lot of taxis in La Paz and depending on where you decide to stay but even if you stay in areas like Costa Baja, which is the farthest hotel out or town, they have a shuttle that will take you to and from town once or twice a day so that’s not really an issue, either. If you live by the malecon (boardwalk), you can easily walk the malecon and find supermarkets, movie theaters, etc.
(Dune buggies in La Paz, Baja California Sur Mexico,pictured.)