When cars were first introduced to US streets there were pedestrian clubs who wanted them regulated as much as possible. Sure, one could argue this was because it wasn't that common to own a car back then and therefore those who didn't liked to "stick it" to those who did.
However I think it is hard (and unwise) to ignore the role which (car) culture has played in this. Before car culture streets were a thing one shared with pedestrians, horses, carriages and cars. If you change that culture and priorize other things in your public spending for a decade you can end up somewhere entirely else [queue pictures of Amsterdam in the 70s vs today]. This influences culture and therefore the way motorists will treat cyclists.
I am not saying that the nature-side of the nature vs. nurture debate isn't existing. It is quite clear that both sides exist from what we can observe. Thr nature side is much harder and riskier to change in our favour than the culture side.
The way it worked in the Netherlands is a good example. If your bicycle infrastructure is good enough, more people will bicycle. If more people bicycle, more motorists bicycle. This means more motorists understand what it feels like as someone cycling. This in turn means there is less conflict for both sides.