Click to the right to advance the comic. Bosses love 100% attendance, no matter what's going on in your life, so teachers are expected to instill that work ethic. One of my daughters' classmates was lauded for 100% attendance for 12 years of school. I asked how she ever got a driver's license. The kid didn't have one, because it would have ruined her attendance record.
Every place I've ever worked, it was expected that you show up, sick or not. If you are in an at-will state, your job may depend on it. If not, well, your pay might depend on it. This comic is from Work Chronicles.