You will never ever get a reason for being fired in writing here in the US because all that does is provide evidence for a possible lawsuit.
> Is it all related to American culture that the rest of us don't understand?
In part, yes. Here in the US we don't really have worker protections. Many believe it is because of this that we have such a strong growth in business.
It objectively makes our economy more nimble and adaptable, but at the expense of employees.
A perfect example: I worked at a startup in 2000, and we had a bunch of people in the US as well as Europe. When business was down and we had to lay people off, we ended up laying off engineers in the US, because we couldn't get rid of any of the people in Europe quickly enough. We had to pay people for months before they were let go, and they didn't even show up to work. It was great for them, but it was bad for the company and also bad for our growth since we had to pay people to do literally nothing.
To be clear, I think workers need greater protections. But those protections should not be at the direct expense of the company. It should be indirectly through taxation.
But to get back to your question, yes, here in the US, workers are not treated as well as elsewhere. Entrepreneurs and businesses are seen as the drivers of the economy, not the workers.