I really think it depends on family dynamics, not etiquette rules.
If I am a guest at a family home I am a pitch in sort of person. I always will help clear tables, wash pots etc. If I know the hostess is particular in how her dishwasher is loaded, I rinse and stack. If I know how they load their dishwasher I start to load after rinsing.
My kids have been taught since they were little to clear their plates and others, when visiting family and close family friends.
But having said all that, when my mum comes over and has a coffee, the cup is left where she was sitting. But if she was over for dinner, she would be helping clear up.
I cannot imagine anyone in my family bring fast food to my house to eat, let alone leaving the wrappers out. Unless they were bring it for everyone, but still garbage is garbage, not dishes and should be put in the garbage can by the person who creates it.
I do not have a great relationship with my MIL, but I really would not care if she left out a few dishes.