That's because street and cosmic are simply locations or settings and not really power levels. Cosmic settings may have more impressive power levels, but that's mostly because in a cosmic setting, characters have more space to cut loose in ways that they wouldn't be able to in a more densely populated location like the streets of a city on Earth. Street settings are more down to Earth, literally speaking, so characters have to be a lot more careful unless they want to cause mass destruction of population centers trying to get at their opponents.