Hi Andreas
As you might have noticed, there are several ways to map a sidewalk. Either as a as refinement to a highway or as a separate way. These are facts:
http://wiki.openstreetmap.org/wiki/Sidewalk
So, instead of "solving a problem" by deleting an existing sidewalk and adding a tag to the street, you could as well have fixed the wrong or missing tags and leave the sidewalk.
Yes, I know perfectly well. As you wrote: either ... or, but not both of it. I'm wondering how you fix a road tagged with sidewalk=* plus a separate parallel sidewalk without deleting anything?
Finally Selfish Seahorse, just for your information, the Vermessungsamt der Statdt Bern displays/renders the Trottoirs all over the place of the city of Bern as well. Thus, I don't think that mapping sidewalks separately from the street, is so wrong.
http://map.bern.ch/stadtplan/?grundplan=av_farbig&koor=2601047,1199101&a...
They display all the sidewalks only on the plot map (Parzellenplan), not on the city map. On the latter, the sidewalk is only mapped if there is a barrier between the road and the sidewalk (which corresponds to the recommendation on our wiki).
Fully agree. In Bern these is most of the time done by sidewalks.
If this is general opinion, it would be best to add this information to the [local tagging scheme](http://wiki.openstreetmap.org/wiki/Switzerland/Map_Features).
No, map users in front of a screen (laptop or smart-phone) will see only a street. And no Trottoir (sidewalk) at all.
That's only true for the standard layer, but the sidewalks can be displayed too, like on this [ITO map](http://product.itoworld.com/map/126). An option displaying them could be added to the main page.
The question is: are OSM (or Maps.me etc.) users interested in seeing this information by default or don't they find it distracting (because it makes the map look cluttered)?
Sidewalks have sometimes different surface than the street...
This can be handled with sidewalk:*:surface=*. It is even possible to add width and kerb information.
Regards
SelfishSeahorse