Because the Russian bastards are hardcore trained fighters, they're not pissed up - they're completely sober and the French police are too soft to arrest them, tear gas isn't going to stop them. They're far too organised for the police to get at them and they're shielding their faces so they can't ban them using video post violence very easily either.
The media in England, and the FA have to back the England fans. They're making it look like the English are as much to blame as the Russians. The Russian FA have shaken it off and are refusing to take responsibility. French hooligans in Marseille and Nice have been the cause of much of the clashing initially - they attacked England fans who then retaliated, and they did the same to Polish and N. Irish fans in Nice. The Russians have come as a proper right wing mob and have attacked the English who again have retaliated. The true measure of English fans can be seen within the ground on Saturday - singing, having a few drinks but not looking for any trouble at all.
This is a tournament where there have been huge worries over potential terrorist attacks in or around stadia - the French police haven't managed to stop flares or smoke bombs getting into grounds, they're woefully out of their depth and the fact Russian fans could easily get at the English is a joke. That behaviour was reminiscent of Heysel - except the stadium could at least cope with a mass English scramble to get away.