I used to travel alot for work and noticed that this phenomenon is also regional. I was blown away on my first trip to Ft Collins, CO because I was standing in line at a supermarket and the woman behind me started talking to me like she had known me all her life. If I tried to start a conversation with anyone in a supermarket line here in Boston, they would either completely ignore you or sue you for bothering them. New England is definately the most unfriendly area of the country I have ever been. Out on the road here I almost never get a return acknowledgment from another rider, on the MUPS it's probably less than 50%, and that is usually a family or older person, never a roadie. Actually the best thing about riding on the MUPS is that the little kids will always talk to you as you pass them.