From what I'm seeing here in Europe, the fines for driving with a phone are seldom applied and outside a handful of countries aren't even that large.
Also infrastructure for pedestrians hasn't actually improved significativelly in Europe since 2009 - the big difference in the quality of pedestrian infrastructure between Europe and the US comes all the way back from the 60s or even earlier, so it doens't explain a change of trend on the US but not Europe in 2009.
I'm leaning more towards the "oversized light trucks are dangerous as fuck" theory since, well, they are and the trend to see more of those on the road hasn't happened in Europe but it has in the US.