Why does US have the system of employed at will where you can be terminated at anytime for no reason? ?

You seem to think jobs are created solely for the benefit of employees. They are not, at least not as far as how the US has worked over it's life. Jobs are created by employers for the benefit of employers/business owners. Employers hire employees to fulfill company's goals and will pay employees what employer thinks their skill set is worth to them. 

The only employers that can keep on employees that can't earn their keep is big business. Even then, this is often how small business can compete and get a leg up on big business. Big business often becomes hopelessly bureaucratic, resulting among other things, holding on to types and number of employees that aren't directly helping the business' bottom line. 

In normal times, there are plenty of jobs for skilled workers and unskilled ones to go for work that is needed. 

This being said, There are protections and laws helping employees against various form of discrimination like racial and sexual discrimination, but not to insure you can support a family and/or mortgage. That's YOUR job to live within your means before taking that job in the first place. 

america has a free for all mentality where money equals power and upper managment become souless  because there is no one to put them in check . This country has turned into a greedy machine that never stops . america is one nasty country  

Americans are also free to quit, or terminate their own employment at will.  We are also free to choose any employer based on our personal standards.  We are also free to start any business at any time and be the owner.

Those who complain about right to work are usually those who are allergic to work in the first place and want something for nothing.

In civilised countries employees have workers rights. In the USA you are a slave to your employer.

Because that's how republicans;ican politicians reward their donors. 

Even under modern union contracts, where the worker is supposed to be protected, the employer can fire you for no reason, without notice.

Compared to working for the same corporation in the EU, without an employment contract in the US, you are hostage to the job you have for living expenses and expected to find a better one while doing.it. 

That is what the smart people do that didn't make anything of themselves they want to tell the owners of the business how to run it.

We are generally opposed to socialism.  Employers engaged in free enterprise have the right to run their businesses profitable.  There is some limited non-discrimination law.  Yes, many people have families, mortgages and both parents work.