This is very true. I guess the first U.S. states hit very hard had the advantage of watching what was happening in Italy. China as well, but a lot of the info there was censored and we didn't find out much until we were already hit very hard. I remember watching what was happening in Italy, especially in early March before we went into lockdown here. Doctors there were warning doctors over here to get ready, and sharing techniques, etc.
And what mousefan73 said about the multigenerational housing situations in Italy and NYC really does explain how they were similarly hit so hard. Same for parts of Miami, and Southern California as well.