Ok. Instead of just criticizing, what's your solution? Don't say just throw more money at the problem or hire more teachers. Pretend you're the teacher. If you tell the principal, "just hire more teachers," you'll be laughed at to your face.
So, what is your solution?
You going to investigate every tardy? Every kid will say it's not their fault. Some will be telling the truth. Some will be lying. How do you separate the two? Do you call the parents to verify the excuse?
How quickly can you do that? Can you perform a mini disciplinary investigation in five minutes? Let's assume you can. Well you have 30 students in each class and five of them are late. And you teach six classes. So you have 30 tardies you need to investigate, 5 minutes each. You've just signed yourself up for two and a half hours of phone calls to parents. And many you'll have to call several times, as they work their own jobs and aren't available at the drop of a hat.
So what exactly is your solution? It's easy to criticize. But if you're going to criticize, you should propose your own solution, if even just to indicate you have any idea what you are talking about.