It may be intended (at least as originally used) to evoke the concept of strict liability, which is kind of what Fyralti was getting at. For instance, if entry is forbidden on a strict liability basis then if you are found to have entered you will be penalised irrespective of intention, circumstances or consequence. Maybe you have been chased in there by a pack of wild bears. Maybe you were kidnapped, locked in a car boot and then released in the forbidden area. Maybe you were only in there for a fraction of a second, or the reason for prohibiting entry wasn't relevant during your visit (e.g. you caused no danger to yourself or anyone else by being there). Doesn't matter, you still get the penalty.

I suspect though that as generally used it's just inflationary, intended to somehow beef up the "forbidden" without actually meaning anything.