OTOH, if an instructor no-shows, he gives you the next lesson free.
If he does it again, he is likely to be fired.

Man, you guys are tough. But it does show a serious commitment to the
student. We have instructors who are habitually late or no shows. No
one does anything about it. It infuriates me to see a student hanging
around the lobby for hours waiting for his instructor.

The problem is, we don't want people who may be sick or otherwise
unprepared to fly to feel like they are being forced into flying
anyway.

Yep, that is a concern. I'm trying to figure out a way to respect
usage of the resources (the airplane and instructor), yet still allow
them to make the safe decision. The key may be to flag the abusers.