But Aitch that's not the point.
I have no doubt you would be a respectful user of the loo, as would me and my incredibly well trained children. But a shop owner could not tell that from looking at you.
Many are not. I don't know what proportion (about a third perhaps?)are messy.
You did not answer whether you would be happy for a steady stream of strangers to ask to use your home loo.
What is the difference between your home loo and the one in my mum's shop?