They want to make you uncomfortable, and then desperate, putting your route back to warmth and safety in the gift of the agents of the state. They decide when you can get back to civilisation. They decide when the old people can get warm, when the diabetics can get their insulin, when the kid having a panic attack can go home to her mum. It's a way of making you feel small and scared and helpless, a way for the state's agents to make you feel that you are nothing without them, making you forget that a state is supposed to survive by mandate of the people, and not the other way around.
I'm being more than a bit hyperbolic. I'm not an anarchist, and I doubt very much that I'll ever actually be one. At the moment, I'm more afraid of the callousness of the average citizen than I am of the malicious strength of my government (or the governments of our Western European allies); and I don't see that changing any time soon - though I do recognize that a lot of that has to do with my own personal level of privilege. However, I have an ambivalence that is swiftly heading toward distrust when it comes to police and police action, especially large scale police action at the behest of the state. Any state.
There is something terrifying and immobilizing about recognizing how little recourse we as people have against our governments - even those that claim to be representatives of "the people", that large nebulous group that is always being trotted out with rhetorical flourish to assail or support a political point or a politician's plans and ambitions.
What enrages me the most about this particular incident is who this form of oppression happened to. These weren't seasoned and hardened political warriors. These weren't "professional" protesters. These were children - teenagers the age of or younger than my sisters. This is a group with little political capital, because they have yet to be able to vote. This is the group whose political activism we as a global community should nurture and encourage and recognize as being key to our good future.
What the British police did to these teens, who took the chance to try to make their voices heard and their presence felt, is despicable. The message they imparted was loud and clear - Sit down, shut up, and take whatever lumps we as a government decide to give you. Do not organize. Do not become politically active.
This is how states create apathy. This is how states destroy idealism. This is how states betray their citizens.