This is a very frequent issue: the routing algorithm simply uses the shortest path between A and B, even if that means walking on the main road.

The only way to force using sidewalks is to add an explicit access restriction on the road; we can only do that if we have checked that removing the road from the routing results will work (i.e. there are enough sidewalks to bypass it entirely).

Routing algorithms from the osm.org website do not use real-time data; we should wait a few days that they refresh data, so that the "foot=use_sidepath" tag will be taken into account.