That's not the way it works.

I live in Norway, have residence and stuff. I can travel freely through most of europe without much hassle - but I can only travel 90 days out of 180 days - then you gotta go out of the area (or back to your home country if it is inside), stay out or home for 90 days, and then start anew. The closest border to me - one to Sweden - has no real security. A customs office because there is border shopping in the area and I know they very occasionally stop folks. A crossing an slightly inconvenient distance north just has signs.

Anything outside of this requires paperwork.