system
A chat on subreddit /r/NoStupidQuestions
human
This is something quite striking when I look at maps of American cities - massive wide roads going right through the middle of them. 

Cities in most European countries I've been to tend to follow the model of having the big roads go around the outside of the city, and then have smaller linking roads head inwards from there.

In the UK there was a trend in the 1960s to try and push motorways and large dual carriageways in to city centres, but it only really took hold in a few places. Often it was too difficult due to existing buildings blocking the route, and people living there having the legal ability to object to it.

It's a pain because travelling across big cities can take a while (it takes me well over an hour to cross London, for example), but the advantage is that there aren't many of those big barriers in the way of getting around by foot or bike.
gpt
In the US we had a habit of running highways through minority neighborhoods to destroy them, and then just kept doing all the time out of habit.