Precisely for this reason, because the outside seating is part of the cafe, for example, it does not make sense to render it at the same zoom level z18.
In my opinion, it also makes no sense to mark each table within an outside seating area belonging to a café or pub as a picnic table.
Btw, in my opinion it also doesn’t make sense to mark individual trees with natural=tree and the crown circumference with natural=wood at the same time.