I do feel it's important to teach manners and respect, so I do teach them to say please and thank you. It may be confusing, but I feel the more quickly they begin to use these manners, the faster they will sort out the cultural intricacies involved. I have a 21 month old in my care who is one of the most polite children I know...always says please and spontaniously thanks his friends for giving him toys etc. His parents have taught him this and I reinforce it and I think it's great. They do find out that "please" does not guarantee a "yes", but no "please" guarantees that they won't get it. It's all part of socialization in my opinion. I don't think of them as rude if they don't say it...they are just learning still and require lots of reminders.