Not everyone is a programmer in the Valley or East Coast that can just Slack their manager "will be an hour late today because X!" and everything is fine. For the vast majority of people, even white collar employees, not being at work at 9 a few times may mean termination.
That's very true. Many workers have to go to work with medical problems, take desperate measures if they have car issues, and lose their job if they get arrested.
If you've already missed 1 day for "my car broke down" and another for "I was vomiting", that one time you need to get the kid to school might be your 3rd strike.