Well, from my point of view, that's on the routers. I.e. it is the responsibility of the data consumer to (fill in the blanks from)  the local legislation rather than for (every single) mapper to map the legislation (on every single object). There are several good reasons for that:

1. it is much more effort if every single mapper tags information derived from legislation on every single object than if surveyors just tag what they see on the ground.

2. thus, as many mappers are involved, this approach is pretty error prone

3. when legislation changes: A huge problem. Imagine if that Georgian law changes! As the source of the information is usually not recorded, you don't know which occurances were mapped because of a sign or because it was implicit! Ooof! That's really the main reason to not map legislation.

It is also mentioned in the article on good practice:
 https://wiki.openstreetmap.org/wiki/Good_practice#Don't_map_local_legislation_if_not_bound_to_specific_objects

Routers, by the way, try to determine the default speed limit when no explicit maxspeed is tagged in a country-aware manner, by the way. Check out 
https://westnordost.github.io/osm-legal-default-speeds/#tags=lit%3Dno&cc=GE
if you are interested. GraphHopper is using this, Valhalla has been looking into it.
In general, routers DO have the ability to have country specific defaults, just someone needs to provide that data.

Anyway. This is not a hill for me to die on. If I didn't convince you, maybe I can convince you to somehow mark that the foot=yes derives from legislation and/or actual use, rather than a sign, in for example a "note:foot=No sign, but actual usage" or similar.
