My city has amazing bike infrastructure: mixed use trails with no cars, bike lanes on all streets, tunnels and bridges over major thoroughfares (really it’s pretty insanely good and yes it’s in the US of fucking A).

People still ride on the sidewalks like morons. They ride the wrong direction in the bike lanes.

Bike infrastructure is essential but also not totally sufficient. You need a significant enough number of people using them that there is a culture for it and tribal sharing of knowledge around it.