Bins, rubbish, man holes, street signs, uneven surfaces etc etc ruin bike lanes.
Bikes are great when your development pattern is Netherlands-like: Not dense enough for serious public transport to the home, or to do everything on foot, yet not so light that many trips go past 10 miles. I bet there's a few large metro areas that could support this, but in a lot of the country, it's not about unsafe lanes.
The modern suburban arterial often has light cycles measured in a few minutes, which adds up if you're hitting a bunch of them.
Dedicated bike infrastructure, even at high volumes, does not require coming to a full stop, so while the top speed might be lower, the average is more competitive than it appears. And grade separating a bike lane is a lot easier than a whole suburban road.
A lot more people in this world live in the tropics than the frigid north.
The US has some of the most bonkers bike lanes I’ve ever seen; my favorite is a bike lane sandwiched between a main travel lane and a high-speed right-turn slip lane.