I live in Illinois. in the 90's, in high school, you could have 10 unexcused absences.per semester. after that, you didn't get credit for the semester. vacation (however educational) was not an excuse. a doctor's note was.
my word was not. if my son was sick, I had to take him to the dr. and pay $40 for the dr. to tell me that he had a fever, have him drink fluids and get plenty of rest.
when I was in high school in Illinois (back in the early 70's, private school) my mom used to let me "cut" for opening day at Wrigley field . (see, there was her big mistake...had it been Comiskey...I married a white sox fan). (I got good grades, so she thought it was ok)
one year the school counselor went to the game to "spot" truants. (tough job for him, huh?) I was seen and suspended. my mom had to come to school and she raised holy heck. the Dean said calling in wasn't enough,she should have written a letter ahead of time requesting it, as other parents would do so for a family vacation and it was excused. my mom said I had her permission and it wasn't their business why.
so I guess laws in Illionois have gotten stricter. (maybe cause of my mom!)