If someone is told "if you feel some pressure on a joint or any pain, tap. If you feel dizzy or like you're passing out from a choke, tap. That will tell the person submitting you you're giving up and they'll stop."
If the person being choked didn't tap, that's on them. The exception to this is if both hands are pinned and the person can't tap.
The person on top can't tell when a person is "near passing out". They can tell they either passed out or didn't.
If the person choking felt the tap and didn't stop, they're a piece of shit and that behavior is grounds for being kicked out of most academies and being ostracized by the community as a whole.
I've only seen two people get choked out in my nine years of training, and I've never seen anyone shit their pants.