From a consumer angle, you're frustrated that nearly all games in European markets are released on Fridays, y/y?
From a business angle, what tells suppliers to sell on this day or that day is generally all demographics. Trends (current or past) show that, in Europe, people tend to buy more games on Friday. So they adjust sales and release dates accordingly to reach the highest buyer market possible. If enough consumers politely and clearly express that they'd rather buy new-release games on Tuesdays instead, as to match US sale dates, then the suppliers should be at the very lease open to changing the date. To do otherwise would be poor business sense, as the folks expressing their desire are the ones they're specifically targeting.
Mind you, there are probably a lot of other things factoring into what date games in Europe are released, but the general idea is that X day of the week they make the most money, so x day of the week is the best time to sell. If enough folks expressed a desire to spend their money on a different day, the logical solution would be to change the date to better fit the new trend. Barring unforeseen outside consequences such as licensing, distribution etc outside the suppliers direct control, that is.
The real kicker is getting enough folks in their respective countries to sign on to the idea of a mass email/petition campaign. And for them to also realize that it wouldn't be something you could ask the suppliers to do with just one gaming company. It would have to be all or nothing. But, if enough folks from each country went to their respective suppliers in a polite manner expressing their desire to have game release dates move to be more inline with US release dates, you'd more then likely see an effective shift.
Well, at least in theory anyway 