And anyway, why shouldn't a father/mother be able to take a day off for their son's birthday??
No one is saying you can't. You just need to plan your holidays better. It's not like their birthday is a surprise. You get a year's notice each time.
Does the airline CEO - or any of the management - come into work at 0500 on Christmas Day, or on their birthday, or on their family member's birthday? No.......thought not.
Well, Christmas Day is a public holiday, so most non shift workers - and the industry has several - will not be at work. As for not coming to work on their birthday or their family members birthday? I think you've been in the sheltered workshop too long.
Aviation is a 24/7 industry. For some roles in it, if you don't come to work, someone else has to. That's why others prefer you do your rostered shift, rather than them have to.