> In Bavaria we have most bike lanes as part of the sidewalk.

From my experience (in the UK) how usable those lanes are depends hugely on pedestrian discipline. There's one of those running alongside the seafront in Brighton that in my experience works well. The same style of lane that I've seen in and around London generally doesn't work as well: there are often pedestrians on the wrong side, not infrequently looking into their phones and/or wearing headphones.

What makes matters worse is that in the UK the rules are asymmetric: while it's an offence for a cyclists to go on the pedestrian side, there are no rules preventing pedestrians from walking on the cycle path (source: [1]).

[1] http://www.cyclecraft.co.uk/

The solution is to make pedestrians afraid of stepping into the bike lane. Pass them quickly, closely and surprisingly, if they run into something in the process all the better.

I can't tell whether you're being serious, but sadly there's indeed quite a lot of this us-vs-them and people behaving like arseholes to each other.

Not to mention that, in my jurisdiction, if this sort of behaviour led to injury or damage to property, the cyclist would almost certainly be found to be at fault, at least partially.

^^^This^^^

That's taking space from pedestrians instead of cars. I always see joggers, kids with rollerskates and moms with prams on these sidewalk bike lanes. Side parking and bike lanes cannot cohexist on the same side of the road without wasting another 3 ft of space for a door zone. Some of the useful bike lanes are raised a bit like a mini sidewalk separate from the pedestrian sidewalk or have a physical separator like bumpers.

> Eliminates most problems with cars.

Except now every street crossing becomes a death trap because you're outside the cone of visual awareness of drivers.