I am approaching 40., and if a younger guy was talking to me it would not cross my mind that they were hitting on me. I would just think that they were making conversation. Actually when any guy talks to me my immediate assumption is not that they are hitting on me and I was the same way in my early 20s.
Also perhaps as people get older, they develop more compassion and patience. When someone makes conversation with us, we have learned how to make the conversation easier for that person by responding to what they are saying and not looking blankly at them when they say "I like Adam Sandler movies." Nice people try to make the other person comfortable. Would you prefer that we just be rude and say, "Whatever kid I really don't give a f**k"?