And you may or may not be stamped, may or may not be stamped correctly and clearly, and may or may not be grilled on the state the last border control officer left your passport in, in a completely different country.
I've never had a problem getting my passport stamped on request, even before Brexit. The only place where I was clearly told "no" was in Hoek van Holland, and that was the only place where "can I have a stamp please? I need it for the government..." didn't work.
The major issue is that people don't ask if the border police hand them their passport without stamping it. I had a nice chat late one night in Zurich Airport with a very bored member of the border police (the transit hotel is located in the non-Schengen area, hence you need to cross the border to access it, although you can cross freely to/from the Schengen area between 05:30-23:00) about this, and she said that they have a lot of problems with people who don't have stamps and/or evidence of when they entered or left Schengen previously. She was very clear that the stamp wasn't the most important thing, but that you should have some way of showing what you were doing.
I asked if it was enough to show a Google Maps timeline, and she said that it was perfectly acceptable in the absence of stamps, although they would ask to see some additional evidence.
Greece rather more and even more eastern European countries.
Greece is far more mismanaged than some 'Eastern' European countries.