I would say this is a router issue. I am not even sure if it uses sidewalk= tags at all, it seems to fallback to any roads that don't explicitly ban pedestrians. At the same time it indeed over-prioritises footways.

The solution is to keep mapping and keep improving routers. Not to dumb down data to mask router deficiencies. Fixes to the routers may happen overnight, map data - not so much.

The main advantage of Google is algorithms they use for merging disjoint pieces of information (maps, search, timetables etc), not the quality of their map data. And yes, we could learn from them.