To elaborate, I've consistently noticed a blind spot in lemmy when it comes to teachers and education. There is always a consistent failure to recognize the hard limits of available resources. The common wisdom here seems to be that a local tax base can support an unlimited amount of education spending, and that any problem in education can be solved by throwing more money at the problem. "Just hire more teachers" is the lazy zero-thought solution trotted out to any issue in education. I think it comes from lemmy's left-leaning politics. Which is fine. But even socialists need to understand the concept of opportunity cost. Even if the economy was entirely state run, there are still hard limits on available resources.
There seems to be a great inability to recognize that teachers are actual human beings working very real jobs. And every time you tell a teacher, "the solution is to hire more teachers," you are betraying the actual teachers. Because the teachers know they have to actually work around real-world limits in resources. And every time you tell a teacher, "just hire more teachers," you're indicating you are not seriously attempting to address the real challenges and limits of education. (I realize you didn't explicitly say it, but your comment implies that resources are infinite.)
One thing teachers have to do is to design their classroom instruction and policies around the real limits of available resources, and that includes time. Often times you will deliberately write policies to require little investigation, simply because there aren't enough hours in the day. For example, your suggestion was to follow-up after class, but that's still time the teacher will have to spend litigating every excuse. If there's five students late in each class, and you teach six classes, and it's five minutes each? That's two and a half hours of phone calls, just for one day's tardies!