Yesterday we were in the car for several hours. My husband had the radio turned to a talk show. There had been a Native American on the show the previous day who had answered a lot of questions about Native Americans. A lady called in and said the Native Americans wanted to be buried with their medicine. She said she didn't know why they'd want all those bottles with them, but that was what the Native American had said.
People can be listening to what is said, but still have a totally wrong idea about what they heard.
Another problem with communication is we want people to guess. "I'm going to the appliance department. Where do you want to meet me?" This is an improvement over wandering off or both people going to every place in the store. You can not imagine how uninterested I am in lag screws...even if I need some. I don't look for them, I find somebody who works there, tell him/her what I want, they either point me to it or guide me to it depending on how bewildered I look at the time, and I'm finished. But that is also how I look at appliances or anything else. Find somebody to talk to about what I want, get it, and go. There are times I know what I want and know where it is. But talking to people is good. Listening to what they say is good.
"I'm going to get some trail mix, would you like some?" That's easy enough to say and is polite. There is nothing wrong with being polite to people who are around you all the time. There's nothing wrong with being polite to people you're never going to see again. It is actually a little faster than being rude.