The problem with this is that car drivers usually just assume that the cyclists could just safely use the bike lane, while in reality many bike-lanes are statistically more dangerous than just driving on the road.

In Germany there used to be a a general obligation to use bike-lanes when present, which was overturned by court, because of the safety argument.

As a cyclist I'm harassed at least once a weak by drivers who think I should use the non-obligatory bike-lane. This makes it very difficult to consciously chose the safer road instead of the (too narrow, too badly lit, too close to foot-traffic, too damaged, full of glass shards) bike-lane.