Because you haven't earned the right to, seeing as you don't know what you're talking about, and because complaining about it makes you sound like a little bitch. Instead of complaining, do a little research about why things are the way they are.
Then you can complain.
It's not as much complaining as it is being upset. I have the right to be upset that we have to pay more but I'm not going to go to the head of video games or whatever in PAL territories and demand them to lower the prices of games everywhere.
It's like having your dog die of some kooky illness. You can be upset, but you cant just complain to God and demand he make it alive again. It can't happen. The economy is why we can't have games as cheap as the US and we have to live with it. I think we are allowed to voice how upset we are.
Eh. There's always EBay.