As I recall, that's because it's basically impossible to have a US rewards card in Europe. European authorities tightly cap interchange fees (the fees that come out of the merchant's end of the deal).
US issuers are much less regulated. In the US there are cheap cards that offer no perks and take a small (0.2-1%) cut from the merchant, and the perks cards that have lots of perks and take a bigger (3.5%) cut from the merchant. The CC companies, naturally, want more people to use perks cards so they get more of a cut, so to encourage consumers to use these cards they give some of it back to the users in the form of these rewards.
This model recently came under attack when a whole bunch of merchants brought an anti-trust lawsuit against Visa and MC for their requirement that if you wanted to accept the cheap cards you had to accept the expensive cards as well, merchants want to be able to accept the cheap cards and reject the higher tier cards. The negotiations about that settlement continue, so we'll have to see how it all shakes out, but it could result in a major limiting of American reward cards. Or maybe not, always in motion the future is.
The EU parliament passed a law capping interchange fees at 0.3% (for local personal cards, business has some other limit that I don't remember) so there is just no money to offer rewards to customers of European banks. Much better for merchants, lower prices overall mean probably better for poorer folks, worse deal for wealthy people with good credit who pay attention and pay their bills in full every month. Speaking as an American one of those people who benefit from rewards cards, I think that it is better for society to go with the European choices than the American.