I am a licensed professional engineer, and I will NEVER affix my seal on a street design with a bike lane that has no physical barrier separating the bikes from the vehicular traffic -- for exactly the reasons you've stated there.
I was just thinking the same thing, no physical barrier is just asking for an accident. I believe it to be foolish to allow bicycles on any public road with a speed limit over 20 mph. A quick search shows the average speed in a bike lane to be 12-16 mph. Evidently drifting outside your lane is so common that most states now have rumble strips on the outside of exterior lanes to let people know they’re drifting outside the roadway. We’ve got a lot of two lane blacktops in the rural area’s and it’s pretty common to come around a curve or over a hill and find a couple of folks riding bicycles in the road. Had a local female Doctor got killed a couple of years ago nth of town riding a back road. Had a young lady get killed last year riding in a service road by I-20.
In this case, there was a physical separation.