Maybe it's a different culture, or matter of car and people density, but in my country (Norway) most people cycle on the sidewalk. Including kids of course, from the age of 10 they can cycle to school instead of having to walk.

Many footpaths here are also officially designated "cycling and walking paths". Generally the only cyclists you see in the road are sports cyclists in racing bicycles and tight skin suits.

The thinking here is that cyclists and pedestrians are both "soft traffic participants" so they share a space, while "hard traffic participants" like cars, trucks and motorcycles are kept separate.

Pedestrians do have right of way over cyclists. As the heavier faster party, cyclists have the responsibility to avoid conflict, by giving right of way, and slowing down and/or chiming their bell to signal their presence before passing pedestrians.

Personally, if I was told that tomorrow I'm only allowed to cycle on the road, I would get rid of my bike. If I'm gonna be on the road full of lorries busses and SUVs going 60kph, I'd rather just be in my car. It's just not worth the risk and constant peril. This is in a more suburban and industrial/commercial setting, where the sidewalks have gaps to buildings, and pedestrians are far apart.

I can however see how in a dense, crowded downtown area where the cars mostly drive slow and the sidewalks are dense with people, that cycling in the road makes more sense.

Thinking about it the only roads with 30kph limit and a sidewalk are in the very center of the city. All other places with 30kph are basically neighbourhoods etc where there are no sidewalks and everybody shares the road. Roads here with a dedicated sidewalk also have higher speed limits that what a casual cyclist can achieve