While at University an instructor told our class if we missed 3 classes it was an automatic Failure of the class. Did not matter if you were carrying an A average; third missed class sunk it all. He terrified everyone.
Wow. If I went into a class and the prof had that on his syllabus, I’d drop it in a heartbeat unless it was a class that you had to have for your major and he’s the only one that ever teaches it (which is usually the case for nutjobs like this). It can’t be absolute, though. If a family member dies, you have the right to attend the funeral. Also, if you’re sick. That’s written into the law. Of course, fighting a prof (especially as an undergrad) carries some serious peril and who’s going to litigate it if the administration won’t put him in line. The only thing you can really do is avoid him like the plague if you can.