Hmmm. I think I'd keep on inviting the girl over and I think her mother sounds interesting. Not sure I like the implicit "telling you what to do" in the 'phone call but I quite like having a few quirky progressives around - makes for an interesting mix in the parenting world. How dull if we're all the same.
What did you reply? for what it's worth, here is one possible reply:
"While I appreciate where you're going with trying not to enforce "manners" on your child as an empty form, without reflection, in a top-down, power-inflected manner - and I do get that - without thought, "manners" becomes nothing other than an outdated class signifier - and often a signifier of the lower-middle-class verbal symbols of the early twentieth century at that - I approach the idea of "please" and "thank you" differently.
My belief is that we live in a society that devalues feminised labour, and those carrying out this labour - primarily women - often to the point of attempting to render this labour actually invisible. This has many deleterious effects.
I believe it comes to something of a crisis point in the labour of mothers. I may be wrong, but I do think one of the things we should teach our children is that the work we perform - for them - is real. One way of signifying this is through "pleas" and "thank you". "Please" signifies that we are free agents - able to donate our labour, and perform the task, for them, freely - or not. It renders us - mothers - visible as agents and subjects in our own right - and it renders our labour visible.
It also teaches children, with the "thank you", that to be given - donated - this labour, does not indebt them, leave them "less" as human beings, or give them a voided subjectivity. In short - we are teaching them, with "thank you", that the (masculine? patriarchal?) concept of subjectivity is not the only way to conceptualised oneself - that that is a paranoic subjectivity. In fact, we can think of subjectivity as implicitly relational, always indebted, co-mingled, extending towards others and from others, in a comples, inter-dependent web of gifts and debts - none of which need necessarily be diminishing.
And so I tend to use "please" and "thank you"."