I never really pay attention to these bounty challenges. Are those rewards reasonable? They seem incredibly low compared to the work involved. I have seen locally sponsored hackathons with higher total prizes.
Compared to the $1m netflix prize from 2006, $3.5k seems like a meagre bounty.
There may be the case where someone has already been thinking hard about solving similar problems for the last couple of years, and this challenge falls fairly easily into a framework they've already got in place, so it is relatively quick and easy to crank the handle to generate a challenge submission (or a paper or whatever).
At the same time, there isn't much of an outside market for algorithmic bias info in the same way there for security vulnerabilities. Probably the biggest effect of this reward will be to pull some grad students who were going to study algorithmic bias anyways towards studying Twitter specifically - after all, there aren't any rewards for studying the algorithmic bias of other companies!
It's a no risk way to add a few constraints to the practicing you're probably already doing and if you're lucky maybe you'll earn a few bucks too.
Average total comp for a novice AI engineer is about $300K. That's over $1000 per weekday.
If they made it so the expected value of entering was comparable to the amount someone could make in their day job / as a contractor, I'll bet they could attract more & better submissions.