Why so much litter?

As somebody that is new to the UK and Manchester, I am genuinely baffled and disappointed with the amount of litter and trash on the ground.

My main question is, WHY?

Are people unwilling to hold onto their wrappers and bottles until they get home?

Is there a sense of futility (there is already trash on the ground so it doesn't matter if I add)?

Is it because people are so far removed from green spaces in the city that they don't understand the impact ?

Does the city make efforts to clean up the streets ?

Curious about your insights :)