In most countries, walking on a controlled-access highway[1] is specifically illegal. Why should it not be marked as non-walkable just because there's no signage?
[1]: https://en.wikipedia.org/wiki/Controlled-access_highway
> it's basically a highway with no sidewalk would not matter.
"Basically a highway" and "a highway" is different!
In my experience all highways have markings explicitly banning walking (among other things). So it sounds like OP was making a judgement call based on the fact that there's no sidewalk.
I have the unfortunate experience of walking alongside certain roads without sidewalks. It's not fun by any means but I wouldn't want OSM to outright say that it's not walkable.
Of course it maybe "actually" was a highway.
In the UK you can walk on any road except a Motorway. Non of this is signed.
In the UK there are many places to get somewhere you have to walk on a road (even A roads) that does not have a pavement (US sidewalk)
What OP was (probably) doing was tagging roads that aren't motorways and that have no sign banning pedestrians with `foot=no`, which is only supposed to be used in situations where walking is illegal or impossible. Eventually more experienced mappers noticed what OP was doing and reverted a bunch of his edits, which isn't a great feeling, particularly if you've been mapping that way for a while before anyone noticed
(If OP was using StreetComplete I'd blame StreetComplete for this more than the OP. They used to have a quest for pedestrian walkability that was poorly worded, which they've since removed because it was leading to exactly this kind of confusion.)
Your explanation of why edits were reverted makes sense
So for example, you'll see a sign indicating cars are OK for a freeway. That means, heavy motorcycles and scooters are NOT ok. You can only take your heavy motorcycle on it if it also has a heavy motorcycle sign. But SOMETIMES they'll use the slightly different motorcycle sign which means scooters ok. Well, if it's ok for scooters, it must be ok for heavy motorcycles as well, right? Wrong! Heavy motorcycles must then take the car lane, if there's a lane marked for scooters.
Also sometimes there's a road marked no cars! Scooters ok. Heavy motorcycles? Who knows!
As for pedestrians: lol just die
Cars ok, heavy motorcycles ok scooters not ok: https://taipeiscooterrentals.com/wp-content/uploads/2026/01/...
Cars ok, heavy motorcycles ok, scooters not ok by implication: https://blog.calebjay.com/posts/rent-motorcycle-taiwan/cars_...
Quick, google is telling you you need to cross this river, are you allowed on this road or not??? https://www.google.com/maps/@25.0756527,121.6435485,3a,75y,9...
Time to head back to Taipei proper after hanging at e7play, let's cross the river... oh wait, there's 600 cars behind you blaring their horns as you enter this intersection, which way are you going? Can you go straight?? Who knows! https://www.google.com/maps/@25.0722621,121.4934581,3a,75y,4...
I've had plenty of friends bicycle into places they apparently aren't allowed to. There's no sign that says no, but the bicycle isn't allowed by the implication of some combination of allowed-vehicle signs that are lacking a bicycle-allowed sign.
Maybe it was such case?