Each year, every person gets one individual day where it's all about them. Birthdays are celebrated by nearly 90% of the world's population. I can only speak for myself, but I know that having to work on a day all about you is dreadful.

I believe that every individual should get their birthday as a paid time off day. If you don't celebrate your birthday, it's just a free day! I don't know a lot of people who wouldn't take a day where they're getting paid to do nothing. 

You only get so many birthdays, so I believe that getting your special day off to do whatever you please, would benefit work environments. The gratitude that employees would feel to not have to request their day off, with the possibility of it not getting approved, would improve relationships between employees and bosses.