I can´t speak from personal experience (since I hold an EU passport), but land crossings generally earn less stamps.
Germany-Poland by train - the border guards didn´t even have the equipment to stamp, so it doesn´t have anything to do with me being German.
The Poles did stamp me, however, last week at WAW
A friend of mine (Australian) entered Czechia on land and did not get a stamp. He left via PRG
airport, where he got an entry and an exit stamp simultaneously.
I left Estonia and Latvia by bus, getting no exit stamps, only entry stamps from Latvia and Lithuania. Again, no special treatment for me, the American sitting next to me was treated just like me. But when I left Lithuania by air, I got an exit stamp.
I did Austria-Slovakia-Hungary-Austria by car. Result: one meager stamp (entry Slovakia).