What would you do if your company demanded money from you every time a coworker had a birthday?
It’s nice to celebrate someone’s birthday. It only happens once a year, and everyone deserves to feel special. You would hate for nobody to acknowledge your birthday, so you do your best to celebrate others. And this might even extend to your coworkers. Maybe you’re close enough with them to know when their birthday is coming up, so you can bring them a cupcake or send them a nice message. Or maybe, if you’re especially close, you get them a gift. But odds are, nobody is expecting you to do that. You know each other in a professional setting, so you probably have some boundaries up. One of them is, most likely, spending money on them.
This would be especially egregious if you were forced to spend money on your coworkers. You come to your job to make money, not to spend it. And you certainly don’t want a mandatory birthday tax immediately deducted from your salary. But that’s what happened in this story.