India is the only place I ever travelled to, that controlled visas upon leaving the country. Like what, you are at the airport, behind security, with a ticket back to Germany in hand, with a German passport, and now they have doubts about the visas you got from the Indian consulate? What are they going to do, hold you up and send you back on a flight paid for by the Indian government or what? Really crazy.
Overall, kind of logic so, because how can you leave a place you didn't enter in the first place because you had no permit to enter it? Mind blowing!
This is not that unusual. It happens to me every time I forget to hand over my Dutch residence permit with my (non-EU) passport when leaving the Schengen zone from Schiphol. The border guards are absolutely meticulous about flipping through the passport looking at the entry and exit dates in the hopes of catching a potential overstayer. They're almost always super disappointed when I realize what's happening and hand over the card.
The threat isn't "we're going to keep you here because you weren't allowed to be here," it's "we see you have overstayed your visa and now we're going to make sure you catch your flight out and ban you from ever coming back."
Thailand checks on exit for overstay requiring you to pay overstay fines on the spot in cash. Ostensibly to stop illegal workers, because the best way to stop that is apparently done by the immigration department, by making work visas hard to qualify for and a bureaucratic nightmare to actually get, and checking tourist visas on exit after the illegal work has been done and enough money to cover the fines earned. Because the Labor department has no enforcement force.
Overall, kind of logic so, because how can you leave a place you didn't enter in the first place because you had no permit to enter it? Mind blowing!