I think this is because one of my proposed changes when we launched was to remove bounties from Meta. We've had a dozen or so bounties here on Meta and most of them were attached to feature requests and sort of fizzled into nowhere as none of the bountied requests have been granted (and some have been marked as declined).
There was one exception - about two weeks ago Jonathan Sampson started a bounty to create a "tweet this" button with Greasemonkey. Though there was only one response, it did provide a working solution, so I think that this is perhaps the only positive resolution we've had. On the whole, I think that the Meta community is much smaller than the other sites, and even though this was a neat idea, we just don't have the critical mass to make it a continued success.
I therefore submit that my initial proposed change to remove the bounty system from Meta still needs to be done.