I live in Sweden but my girlfriend is from Seattle so I have visited there a couple of times. There are a few cultural differences that I think play a major part in why pedestrian deaths have gone up in America but not elsewhere.
As already mentioned in this thread Americans tend to be more relaxed about using their phones when driving. It didn't seem like a big deal to read a text message or anything.
Another thing is reflective clothing. Driving at night in Washington I saw nobody wearing anything reflective at all. Here in Sweden outside of city centers at night more often than not pedestrians will wear something reflective to actually be visible.
Lastly the drunk driving culture was very different. In Sweden people would hesitate to have a drink with lunch if they knew they had to drive later that day. In America we went to a brewery whilst waiting for the ferry.