I think there is another factor as well: have a look at train stations during rush hour on East Asia currently vs. Europe. 1) the density is significantly higher but 2) nearly everyone is wearing surgical masks now. I think that mask wearing is an effective measure to slow down the spread, acting at the sender side rather than the receiver (which Western people tend to focus on). You can see a similarly lower exponential spread in other Asian nations compared to Europe and I think that masks plus a lesser degree of body contact can explain this largely.