Agreed. The case is much more clear cut for sports than it is for concerts. What you're talking about exists in the form of presale passwords:

http://ticketstumbler.com/blog/presale-passwords-faqs/

Presale passwords allow fans to gain access to tickets before the public sale. However, scalpers can pretty easily acquire them and the sales limits aren't very hard to game. What does tend to happen though is that the investment banker type (is that reference even valid anymore? :-D) can buy his tickets on the secondary market at the last minute from TicketsNow, which Ticketmaster owns, and sometimes the artist receives a cut of those proceeds. To people on Hacker News, market prices makes a lot of sense, but in practice they scare a lot of people away. Fixed prices are why Ebay acquired Half.com & Stubhub. And it's why places that deal with futures or more complex purchasing options like First Dibz have blown through loads of cash without gaining much traction; the people behind those sites aren't the target market.

What's also interesting is that artists tend to make more money from tours than CDs, merchandise, itunes, etc (as the label gets a significantly larger cut of the latter). So maybe there's some behind the scenes pressure to ensure sellouts and drive the type of sales that benefit the label most.

One final thought: if an artist becomes really hot (like the Flight of the Conchords currently) shows can be added...double or tripling supply in a given metropolitan area. The same thing cannot be done with sports.