It's a tradeoff. If you want to live in a low density area and have to drive everywhere, then no, you're not likely to have any mass transit other than a suburb

It's a tradeoff. If you want to live in a low density area and have to drive everywhere, then no, you're not likely to have any mass transit other than a suburb commuter train to go downtown. The alternative is living in smaller, high density housing where there are two grocery stores, three coffee shops, a half dozen restaurants, a pharmacy, a metro station and so on within a five minute walking radius, and have a fifteen minute commute to work by foot or five minutes by bike, so there's not that much transit required. The funny thing is, if we go back to the point that started this discussion, the city of Montréal actually has a decent public transit system, a bike share system, 400 miles of bike paths and is one of the most bike-friendly cities in North America (depending on what source you believe). For those US cities that have low density sprawl (such as LA), there's no real way to have a transportation infrastructure that makes sense; people who are from LA will say it's fine, you just drive wherever you want, whereas Europeans will say it's not a city that you can live in because you spend your life in a car and can't go out and grab a coffee or pastry with a short walk. Self driving cars don't really solve that problem, because you'll still have thousands of people going to work at roughly the same time, and even though self-driving cars can have higher density and traffic fluidity than human-controlled ones, they still pale in comparison to mass transit systems. For example, look at Tokyo; it has at least five train stations that have a ridership over one million passengers per day and has a ridership of over forty million (granted, that number counts people switching transit systems multiple times). If you assume that the minimum surface area that a self-driving car could have is nine square feet (3x3), slightly more than a chair moving around would have, and that you need 5 million of them to have an adequate amount of service, just the surface area of all of these cars, bumper to bumper, is 1.6 square miles. Assuming you put them back to back, eight cars wide, that's 355.1 miles long worth of cars, which is about 40% of the length of freeways and highways in LA county.