Again, notice the assumption of infinite resources. You assume that these resources always exist, and that those resources aren't being used for something else. You fail to recognize opportunity cost.

Someone is going to have to spend 2.5 hours calling all those parents. Whether it's the teacher or someone in the office staff is immaterial. And that someone could be doing other things, like helping a teacher out with instructional duties. If you have 30 classrooms in a school, that means your office will be making 75 hours of calls to parents every single day. You'll need to hire ten people just to call all the parents. Do you really think the best we can do with our scarce education dollars is to pay ten people to do nothing but call and investigate tardy excuses?

Having anyone spend that much time litigating every tardy excuse simply isn't a very good use of tax dollars. There are better things to spend money on that will do more to help kids. Far better to just have a certain number of excused absences and not have to worry about investigating every single excuse.

What isn’t acceptable is just being shitty to children because life isn’t fair. Thats just abuser behavior.

It's a perfectly fair system. You have a certain number of free absences, free late homework assignments, etc. This way if shit happens, students can have a few ooopsies without it affecting their grades. Instead of litigating every incident, you just give a certain number of freebies.

This is a perfectly fair system. It's not being shitty to kids. It's just deliberately designing a system so you don't always have to assign blame.