An obvious factor that is constantly ignored is that LA and NY are international travel hubs, they are were pretty much everyone coming to this country must go through. And most tourists stay in LA and NY, they are by far the most popular tourist destinations. That likely accounts for the high numbers there, sick tourists coming over and spreading it.
I live in LA and this theory is backed up by what I see. The people in LA not wearing mask, not social distancing are overwhelmingly tourists, they are easy to notice and are everywhere.
Another data point that backs this up is San Francisco. They have had the same guidelines and protocols in place and have have a tiny fraction of the cases and deaths of LA. If they had LAX, I am rather certain that they would have similar numbers as LA.