How dare these
vapid bastards attempt to take an
interest in your life without reading your
mind first? When associating with
people who are distanced from yourself in terms of interests and respective
age brackets, it will be hard to instantly compose a fascinating and lucid conversation. There will be
uncomfortable silences, particularly when you and the person you're conversing with have no knowledge of each others'
pursuits.
The problem isn't removed when adult strangers converse. Both parties make an attempt to introduce new ideas into the conversation; over the course of the conversation they grow to understand each others' interests. They may then ask questions and share random personal information that will actually interest the other party. The difference between a situation between two adults and the situation you describe is not necessarily that these people refuse to respect you as an adult. Most (but, unfortunately, not all) people are willing to perceive relate to youths as adults if this is warranted. A youth who appears self-absorbed and disinterested in the person speaking to them will not be related to as 'just another adult,' though.
If you have made a decent attempt to respond to their enquiries with more than 1-phrase answers, and perhaps even made polite enquiries as to their lifestyle and pursuits, it's fair to expect your age to become irrelevant within this situation. If you're incapable of doing this, that's okay. However, it does indicate that you still have a little learning to do before becoming comfortable in these situations, and social discomfort is not solely the fault of anyone who attempts to converse with you.
I've felt the frustration of being stuck in this situation and it took me ages to learn this for myself. However, this kind of self-righteousness really angers me; if it wasn't for this I wouldn't be posting a reply node.