Do people stand/walk on graves?

I grew up watching mostly American culture through TV/movies/series. I notice that people talk to a deceased through their headstone, by standing literally above where the person was buried. In my culture it's really disrespectful, all graves are marked around the perimeter of where the person is actually buried....

I am familiar with Cathedrals and people for some reason being buried underneath the floor. I always found it uncomfortable and avoided walking on top of someone unless there was no alternative.

In actual graveyards though, does this happen IRL?