Seems like some of his classmates are enjoying their isekai life perfectly. Those goons would never want to go back. That being said, although the author probably wouldn't have the wits for realising it, but since that other world has been summoning people from Earth for decades, in large numbers, the problem would be known on Earth, with people disappearing mysteriously, sometimes with their vehicles included. If some of those summoned people had made it back to Earth, naturally chances are everyone would know of it. If this was the first time people had been summoned or previously just one or two had been, things would be different, but I got an impression it's a regular occurrence, a tradition you might even call it.
Perhaps, but it's not like the author could do it here, for copyright reasons.