The word "friend" itself takes on different meanings to different groups of people -- especially after the rise of FB -- 1000s of "friends" on a social network is very different from 100s of "friends" you've only met once which is also very different from the ~5 "friends" you see on a daily basis, and much different from 0/1/2 "best" friends who you think you'd do anything for.
I also think it's weird that everyone has to learn these (and other lesson) themselves in their 20s/30s/40s/whenever -- why is there not a compendium of reasonable/decent ways to approach intrapersonal relationships and society in society today? Like a farmer's almanac for human interaction.
[EDIT] - I also think that this is the key difference between sales and engineering orgs. Not that all engineers are introverts or all sales people are extroverts but this choice of expenditure of energy feels crucial to me.