Anecdotal, but: this is probably more of a Denmark thing and not a Schengen thing. I recently crossed French, Dutch, German, and Polish borders on 4 separate trips and had no checks.
Was that an actual check that could catch something, or was that just a useless inconvenient?
Because whenever I enter Austria, the "border check" is just a young grunt soldier from his mandatory military service slowing down cars to 30kph and waiving them through. One time that young soldier fell asleep in his booth with his hand out. Probably too much partying the night before so I can imagine his CO wasn't thrilled when he saw that.
So to me, the Schengen border checks are 99% inconvenience and security theater, and 1% actual security.