UniChris

Indeed - but this is typically only viable when there's a pedestrian route like a sidewalk right beside; unfortunately even then it's a hard sell. We had one that got re-built far too picturesque; it's a nice winding path through a garden and was too tempting for a while compared to the sidewalk a few yards over, fortunately better signage has improved things but there's still another nearby stretch where tourists get confused since the bike path is a gentle continuation of the road crossing while the sidewalk is a sharp turn one way or a less purposeful wander through a park the other.

Actual cycling cities seem to have far more congestion than depicted, even if it's all cycles. The existing ones seem to be primarily designed around the idea of short commutes at very slow speeds. Not a cycle to work to bypass the traffic mindset, but a that is how people get to work one.

There probably is room for something else in the US though, a sort of "bike highways" feeding at longer distances into more congested and dense urban paths. Typically you don't get that many people walking on the remote stretches, though on my really early starts of rail trail distance rides heading out of the city I sometimes saw far more joggers and dog walkers than bike commuters.