Well, in my experience, most of the migrant workers would not understand
“Just bang that shit in there and set it off, an’ if it starts playin’ up, give it a wollop, and if ye reckon the edge’s had it, just gizza shout or grab me guvna. Oh, and if any of ‘em are pissed, just bang in a noggin and get ‘em flush. If you break summat, broom’s about, just whack it all in the skip. Oh, and if they’re fucked, just chuck ‘em. Oh, and minda ya greasy mitts on the inside coating, else QC’ll ‘ave ya. See where that lumpy tosser in the United shirt is? Bogs are just past him. No fag-breaks, coz Wilson’s a fuckin’ jobsworth. Don’t yap when the ol’ guvna’s about, and that’s about it. Aight, just gonna take a slash, and then we’ll get crackin’, eh?”
So, when people do introduce migrant workers like this, I usually then have to explain everything again to them, after the person doing the intro has gone. I’m pretty sure people do this, just out of disregard for the foreigners, or plain stupidity.
It’s a good way to pass the time, if we’re doing something like box-shifting or labelling, to teach the foreigners some of these English colloquialisms, and other words and phrases they wouldn’t have learned in the classroom/from their books.
Like I said, I don’t know how it is in America, obviously with almost everyone in the country being ‘foreign’ in the end, a huge proportion of the English-speaking population could look very ‘un-English’. In the setting of a warehouse in the UK, however, where in many cases a majority of the workforce is of recent arrival from Eastern-Europe, it’s certainly not ‘odd’ to think that speaking differently to ‘foreign-looking’ people makes sense.
If anything, taking zero effort to make allowances for the probable language barrier is more xenophobic.