Uhm, no - when did you try travelling last? I just crossed the border to Germany from Poland(both ways) and there is nothing there. And before that I drove over in January and there was a huge queue because of "checkpoints to combat illegal immigration" and that checkpoint was just a bunch of border guards standing there looking at cars passing by, they weren't checking passports or much of anything really, it's all just theatre.

Also did you forget flying?

I did get checked a few times while heading from the Balkans back to Germany. There are also random checks in buses and trains.

About five days ago, Szczecin → Berlin, stopped, had my documents meticulously examined and asked some typical questions I haven't been asked for a decade ("What's your proof of residence", etc).

I look like a typical WASP programmer in his forties, so no selection bias or something.

What counts as proof of residence in this case? Asking so I could prepare.

mObywatel is enough.

See also this marvel of brain damaged legalese: https://www.strazgraniczna.pl/pl/cudzoziemcy/najczesciej-zad...

I guess it's just random stops or some checkpoints are more stringent than others.

They pull out some cars, last winter I got pulled out at the border when I entered Germany from Austria. They wanted to see our passports and asked where we were going.

They wanted to see a valid national id of any shengen country, which are easier to get than passports (except in sweden, because it's the police releasing both, so might as well just get a passport).

National id is completely fine inside shengen. Please inform yourself before spreading misinformation.