In most cities with good bike infrastructure I've seen you cannot ride a bike among pedestrians, they are limited to roads and bike lanes[0]. Whenever I see bicycle on a sidewalk is most often because road is jammed with cars or it's too dangerous for bikes, if we get rid of (most) cars, this will not be a problem as there will be plenty of space for everyone.
There are two differences:
a) It's something that I can control, as long as I stay on the sidewalk and the cars stay on the street. But I have no control over bicycles on the sidewalks (even if there is a bike lane and it's illegal, many cyclists just take the shortest path, because they can).
b) it's a problem than can mostly be solved by technology. I would like to see automatic pedestrian braking being required for new cars. I doubt we'll see bicycles with any kind of emergency braking system in the next decades.
Sure, in isolation I would prefer a car staying in its car-lane to a bicycle driving all over the sidewalk.
But then, this change doesn't have to happen in isolation. The Netherlands is a great example of a decades-long investment in pedestrian-first & cyclist-first infrastructure over cars. Cycles have their own dedicated lanes, increasingly not just painted on the car-lanes but separated from both the car lanes and sidewalks with elevations. And as they're ubiquitous and well-kept, cyclists have no real reason to drive on the sidewalk.
Cycling on the sidewalk just isn't a problem of any significance anymore in most places in the Netherlands. But when I went to Berlin and cycled there, I often found myself on the sidewalk by way of convenience and safety. The solution isn't to say no to bikes and have cars instead because cars have dedicated infrastructure they stick to, the solution is dedicated infrastructure for bicycles and incentives + enforcement to make them stick to it. It works very well in the Netherlands, which was actually, at one time, a country with tons of development geared towards cars.
Why? Excluding children, most pedestrians who get killed by cars didn't pay attention while crossing the street. That's the no 1 cause for adults. The other one is walking on streets without sidewalks.
A couple of relatively recent studies done in Australia came up with the result that driver error was the cause of collisions with pedestrians/bikes around 80% of the time.
As a matter of simple physics, the only way pedestrians are killed in crashes is because cars are moving sufficiently fast to bring deadly force to a crash— which makes cars traveling at speeds over 20mph in areas with pedestrians the fundamental cause of pedestrian deaths.
