Biggest problem: personal cars are built for safe freeway travel at 60-80mph. So they're heavy as hell (often 4000+ lbs), and physically large. But incredibly wasteful in the city, on 0-35mph urban roads clogged with bikes and peds.

Low speed/neighborhood electric vehicles might point the way.

Where are you seeing all this "free" on-street parking? Out in the Sunset, maybe, but nowhere remotely commercial. Meters are creeping all the way to Dogpatch.

My understanding is that usage fees (gas taxes and the like) don't come come close to paying for upkeep of roads.