Most European cards are chip cards now. (Many of them might require a PIN too.) American cards still have magnetic stripes that are very vulnerable to skimming. But credit card companies (/banks) can't get rid of the magnetic stripes (in a commercially viable way) until readers are upgraded to support chips. In Europe, you'd probably just have a law saying this needs to perform to that security level by this date, and make the companies upgrade -- but the US theme is "stuck in the 70s" for this kind of stuff.

I have high hopes for contactless payments to finally force reader upgrades, because the difference is something the consumer notices and might appreciate. With magnetic strip vs chip, the user experience was too similar.

(Of course, my phone fails to pay about half the time at the local grocery store, but at least the credit card tap works.)