I came here to have a drink and they wouldn't give...

I came here to have a drink and they wouldn't give me a beer because I didn't had my passport on me.
I'm 28 y/o and even when i showed my International license and a picture of my passport they wouldn't let me have the drink.
I understand the rules that if someone looks under 30 he should show his ID, but you shouldn't expect tourists to hang out with their passport all the time!
That's rudeness and shaming.