US as subject pronoun

''Seriously, though, us ladies don't travel light, so if you've got more than two bags, you'll be using the rear seats. Which are pretty useless for passengers anyway.''

Why US LADIES instead of WE LADIES?
Is it acceptable in standard language, or it's sloppy?

This usage would not be considered acceptable in institutional English but it's very common in the colloquial language.

It's sloppy.

WE people find it easy.
They are always looking at US people.

Again, it's the difference between the nominative and accusative.