I'm the same. One time a friend invited herself round while we were at school dropping off our children one morning. I said I'd meet her at mine and she was waiting for me in my driveway. House was a mess, breakfast things all over the kitchen.
I literally sat in a chair from 9am to 3pm while she talked at me, ate my food and drank pints of tea. In my head I was thinking "Please leave, please leave." We left together to pick up the children from school. I felt dazed, dizzy and unwell. I kept thinking surely she must have things to do at home, and I've wasted a whole day listening to this woman banging on and on.
Another example - child comes round to play, Mum comes to pick up (different person.) Instead of quick interaction, Mum plonks herself down and chats to me for a couple of hours while kids are going crazy and my dinner is waiting for me.
Day out with other Mum and her kids at a park or beach etc. Long day out in the sun, tired and dirty. Kids ask if other kids can come back, Mum standing smiling waiting for my answer, they all come back and I'm stuck with them for hours, wrecking bedrooms and asking for food.
Now I invent appointments - popping round for coffee at 11? Fine but I've got the dentist at 1pm. Some people have no boundaries - or shame.