She should stop staying late if this is how she’s treated when she arrives 120 seconds late.

A good rule of thumb for salaried employees is that you can be a little late if you stayed late at the office the day before to finish up a project. Similarly, if an employee shows up 30 minutes late due to an unfortunate commute, they might stay 30 minutes late to make up for the lost time. For most office workers, their boss isn’t going to flip their lid if they show up a couple of minutes late, as long as it doesn’t escalate into something more extreme. There’s a big difference between being 5 minutes late and an hour late, and if the former turns into the latter, you might get in trouble with the suits. At a salaried white-collar position, you don’t «clock in» the same way you would if you were a nurse or a store clerk. In those positions, things can go a lot more awry if a bunch of employees are late, which is why hourly jobs tend to be more strict about timeliness. Whether being late is a big deal depends on the kind of work you’re doing and who you’re working with. I’d be understandably angry if I had to join a meeting at 8 PM from the UK, and my coworkers who worked in America were late. How hard is it to show up to a 3 PM meeting? 

The employee in this story is understandably angry about being scolded by her boss for being two minutes late, especially since she stays 15-20 minutes after her shift ends nearly every day of the workweek.