A big difference you're missing is the I-95 corridor is linear, so you have huge pockets of density all close together along just one single highway / train lin

A big difference you're missing is the I-95 corridor is linear, so you have huge pockets of density all close together along just one single highway / train line, which makes it easier to connect than randomly spread out. Philly is kind of a podunk city for the northeast yet it is denser than metro London, which is arguably one of the top 3 cities in the world. You are kind of proving my point!