the tag leisure=maze is not applicable, but tourism=attraction, attraction=labyrinth could well be applicable to some, this is why I mentioned these.
One tag is probably sufficient to tag those kind of mazes that are set up to walk inside for leisure / pleasure. As the question by @watmildon about the chalk drawing shows, we might want to distinguish those mazes with physical barriers from those drawn, maybe? Or distinguish by size (e.g. you can walk inside vs. you can only look at it because it is too small).