[KozmoNau7]

It is very likely because the connecting bike infrastructure is either not very good or completely lacking.

You can't make good bike infrastructure by simply painting a few bike lanes here and there that "hug the road for a few KMs". You need to look at a bigger picture and make bike-friendly connections between popular hotspots.

On top of this, there's apparently still a perception in the US that bikes are either for kids or purely for exercise, they're not really thought of as everyday transportation. Everyone with an interest in improving city traffic should come visit Amsterdam or Copenhagen. See how infrastructure with a primary focus on bicycles and public transit works, and which design decisions have helped shape city traffic.

An issue further compounding this is the insistence that bikes are completely the same as cars, and should follow the exact same rules. This leads to extremely dangerous lane changes and left turns, because cyclists are expected to use the car's left turn lanes. This danger can be easily mitigated by requiring cyclists to make hook turns[¤] instead. We do this in most European countries, and it's significantly safer for everyone involved.

[¤]https://en.wikipedia.org/wiki/Hook_turn