>

I believe it.
That’s the difference between manners and etiquette. Manners are more about actually being respectful to the people around you. Etiquette is just a bunch of rules you’re expected to follow at formal functions. Rich people have etiquette but usually are used to getting what they want and so are pretty entitled with no manners at all. >

The middle class are a pretty rude lot. I think that’s more due to how they are raised. Working class people are raised that in order to better themselves they need to work hard, be a good worker. 
The middle class tends to be raised on the idea that they need to do everything in their power to be better. Being better includes a sense of superiority and confidence. Which can often come at the expense of basic respect. Particularly for people they see as lesser than them. 
As someone who was boarding school educated you can see it even when you are young. The newer upper middle class that recently came into wealth tend to be rather rude. Where as a lot of the scholarship students who come from really bad Council estates or just rough backgrounds. Tend to be very grateful for what they have.
It’s all just part of the great British class divide. >

Pretty much the same in America too if I'm being honest. >

Can confirm >

Can confirm also. >

Why are the British so obsessed with labeling people by class? >

It's an important part of society. >

Know your place? >

Precisely, but in a productive manner.
Social classes are, at their heart, stereotypes. If you fit the stereotype (with some aspects being more important than others) you fit that social class. 
If you know your social class you can more easily identify the groups of people you're going to have more in common with.  You'll be able to identify where you fit in. >

Usually how it works everywhere.