But WiFi is so ubiquitous largely because cellular coverage is either terrible (in the case of the UK), expensive, or both (e.g Germany). Set one foot inside a building and I hope you enjoy 2G/EDGE (if you’re lucky) or no service at all.

Most US cities have good cellular coverage regardless of which network you choose, and pricing is reasonably competitive. Therefore, in my opinion the need for free WiFi just isn’t really there.