Eh? They are bolted on with screws and get regulary replaced. It's not any difficult than removing training wheels.

Nope, thread starter has a point here. It's not only pedals and screws. You probably would like to remove the front gears and therefore the chain, that requires you to remove the whole rear weel. What if you have a back-pedalling brake hub. Besides that now you have a "hole" in the gear area, maybe full of oil, Also the bike designed to perfectly run with the full gear on. And so on... you may not want to tamper that "perfectly" aligned system if your kid is playing with it. Nope...it's not just about removing the pedals.

Or just remove the pedals and tape one of the cranks to the chain stay so they don't spin and catch the trousers. Did this with my daughter's bike and it held up fine for the month she pootled on it until she was ready to pedal.

Why do you need to remove any gears? You just unscrew the pedal from the arm and that's it.

I'm really not understanding why you think it's necessary to remove more than that.

I've done it on quite a number of different bikes, it really is quite easy.

You'd think so, but having taken apart a couple of bicycles I gotta say it's far more complicated than say taking apart a PC. There are so many seemingly pointless steps involved like removing C clips that don't belong and solving some topological problems to get the chain out. Notice how the chain and the triangle frame are interlinked.

I have no idea how these victorian steam punk contraptions are assembled and sold at a <$100 price point

Are you maybe thinking about cranksets? All it takes to remove a pedal from the crank is an adjustable spanner.

Define "regularly". I've replaced pedals on bicycles I've owned exactly once in my lifetime. That includes the 4 year period prior to COVID that I commuted by bicycle and caltrain. It was much more difficult to loosen the bolts and get them re-fastened than the training wheels on my oldest's bicycle. Not to mention the handling of the chain.

I switch between toe clips(for commuting) and cleats(for longer rides) at least once a month. Why would you need to handle the chain? Pedals are attached to cranks.