Mmmm, I am surprised your DM was washing it as things have changed now. In my day you binned everything that hit the deck.
My DILs and DDs who are all new Mums say that they go with the 5 second rule. Stuff can hit the deck for 5 secs ( can't remember the exact no of seconds) and they pick it up and put it back into the hands of their DCs.
I find this astonishing, but because I don't offer advice and always do as I am told, much against my better judgement, I do the same.
Toast hits the deck, I just pick it up and put it back on the high chair tray.
Fashions in child rearing come and go. I know one thing though, all my years of experience in child rearing, with all my DCs brought up successfully to adult hood, healthy, no fillings, in their 30's , very good jobs, really nice people etc, count for absolutely nothing.
Google rules in all their houses.
Spot on babies face ? out come the Ipad and spots are googled.
So your DM had a lapse. Have you forgiven her yet?