Do you teach your children to say thank you for their meal and may they leave the table?

American here. My kids have great manners that I have taught them. They always have good manners at other people's homes too. (or so I have been told). When their friends come over, the friends follow the lead of my kids. My kids remove their own dirty dishes from the table when they are through. It is just helpful to me. Their friends copy the example. I've noticed that the friends who have family that do lots of fast food, very active, and don't have meal times together, are the kids who have the worst manners. Hey, they don't even know what all the silverware is for. They have grown up eating fingerfood, no need for plates and utensils. They have actually told me that they don't ever use silverware/tablewear/napkins etc.. So, for me, I have observed that the lack of table manners is related to a busy family that does not have sit-down meals.