The UK has somewhat different customs in this area (and possibly different laws). I recall reading a comment a few months ago from someone in the UK talking about how many more cars get through a green light in the UK than the US because the UK drivers are all ready to start moving as soon as the light is green, rather than waiting for the car in front of them to move before taking their foot off the brake. It is perhaps unwise, but if that's the habit, it's more understandable.
No, it's because in the US the light sequence is Red -> Green, in the UK it's Red -> Red+Yellow -> Green so the drivers are reacting faster and skewing the stats.
In fact most are moving on the Red+Yellow part of the sequence.