Go look at a map of Tucson. Look at where the Titan II missile museum is, then look where Biosphere 2 is. Now tell me how much it would cost to build public transit between those two locations, and how many people would take it.

Trailheads are fundamentally incompatible with transit. They might be philosophical opposites. A trailhead accessible by rail is a trailhead I don't want to be at.

Not everywhere in the world is exactly the same. Stop trying to force a top-down solution that works in Europe on a geographically massive city like Tucson

Generally cars are going to be faster (it's point-to-point with no stops to let people on/off), or equivalently, they have greater range for the same time. If your goal is to physically remove yourself from downtown, they let you go a bit further. Also you don't have to deal with someone leaving their mac-and-cheese meal to stink up the bus. Getting away from such unpleasantries is kind of the point.