Similarly helping out in our tennis/hockey club shops during tournaments, as a volunteer, having orders barked at me.
Screw that.
I loudly said the shop was closed to anyone who didn't know the words please and thank you and I couldn't care less about the parents standing around that heard me.
I certainly wouldn't tolerate it and neither would the other women helping out.
In my home it was ALWAYS a case of " in this house we say please and thank you" on the rare occasion I had to point it out to visitors, and the children reacted very well to it.
I don't care whose child it is, no one is barking orders at me!
My children have always had beautiful manners, often remarked upon.
We never had to teach them as such, just by using please and thank to them from their earliest stage, knocking on their door from an early age, meant it was all they ever knew by example.
Excellent manners are a life skill IMO and make life that bit easier to navigate when you have them.