Why are there so many stop signs on American streets?

I'm from the UK where in general there's only a stop sign if it's needed, such as a junction where you can see absolutely nothing on one side. Otherwise usually there's a give way line instead, to let people slow the car right down to look, but not need to stop if it's unnecessary.

Whenever I see a video of an American street, it seems like there's a stop sign everywhere I'd expect there to be a give way line. Surely this is inefficient as stopping and starting increases emissions, and stops the flow of traffic.

Is it really just the American government doesn't expect drivers to look properly? Is it so the police can give people tickets for not quite stopping but still doing the junction completely safely?