Does someone actually care enough to check the slip? The few times I've been late due to things like this (flat bike tire, crazy traffic, train delay, whatever) my boss was just like ...ok try not to let it happen again and possibly documented it somewhere. I have been salaried for the most part, maybe if you're hourly you might get docked the time.
When I have had someone under me and they're late once in a while I don't really care.
(USA)
In schools with minors there may be liability reasons. I used to have a somewhat unreliable commute, so my school was exempted from being legally responsible for my wellbeing for a few minutes after what would have been normal.
