I beg to differ. And I used a bike daily for commute (okay, when it wasn't raining) and a car otherwise.
The roads are for everybody. Bikes, cars, lorries, farmers. We should (and can) learn to live next to each other.
If you aren't a kid or aren't driving a bike for leisure on the weekend, then "separate from the street" bike ways have several drawbacks. Especially if you want to go speedy from A to B.
- often they aren't cleaned like the normal streets. So expect weeds growing into the lane, dog poop, farmers mud remnants, glass shards. Things a car driver sometimes see, but to a much lesser degree.
- kids play there, making the biker need to speed down
- dog owners walk there dogs there. Especially the long telescope lines are bad as bikers aren't usually not that good with rope jumping
- people walk there and if a bike rings the bell, they usually first turn around "What in gods own world could ring on a way dedicated to bikes?" seems to be an important question to be answered. Way more important than just going to the side.
- if a parking lot separates the bike way from the street, then the passengers in the cars just open the doors, not looking if some bike comes
- every street crossing is usually not level with the bike lane. So as a biker you always go 1-3 cm up/down twice for every crossing street. Some bikes have very narrow tires, that's not fun
- at the street crossings the car drivers are used to check for other cars. But they are less likely to check for bikes. This improves currently in Germany, but it's still not at the same level
So if I want to go fast from A to B by bike, I actually prefer to use the normal street. And if I go by car and see a bike then I can understand this. Except if the bike drives intentionally in the middle of the street. Don't do that, drive on the right side (except in UK or so ...)