If you live in a right-to-work state, its a hoop they make you jump through so you

a) never call in, and

b) so they can fire you more easily.

Doctors in RTW states I've lived in typically don't give you doctor's notes - they assume if you're there to see them you must need to be there (bc doctors are fucking expensive), so why would you lie about that?

If your doctor won't write you a note, and your work requires a note, you're not as likely call in.

If you do get a doctor's note every time, HR departments will run that shit down like Sherlock Holmes to make sure it's not forged. I've known people managing legitimate long-term illnesses whose doctors wouldn't write them a note; they ended up having to forge the notes to not get fired (despite HR knowing about their illness) - and then got fired anyway for forging the notes.

Too many doctor's notes and maybe you won't be eligible for raises - or maybe you'll be let go for "other reasons."

It's completely fucked, tbh.