Job? High class? Low class?

Why some people will categorize jobs into low class and high class?
How to define a job is a high class job or low class job?
For them,

If the working environment is good and with high salary

Then it will consider as a high class job

So for them

Those mechanics, garbage workers, cleaning workers are consider low class job

But do you realize something?
If without them
I think you cannot survive

For example

You are a CEO
You work in a big company

You earn a high salary

And you always say mechanics is a low class job
Only those who cannot study well will go to become a mechanic

They need to work in a dirty environment
Always sweating like work in a desert

But one day

If your car broke down
Do you able to fix it??
Yes

You may get a very good result
But

So what!!!!
You don't know how to fix a car!!!
You said mechanic is a job for those who cannot study well

That mean you said mechanic is a easy job la??!!
But why you don't know how to fix a car although you are 'smarter' than them???!!!

Bullshit!!!
All jobs are same!!!
Don't classified them into low class or high class!!!