The thieves post in a public place basically admitting that they stole the item and are more than willing to meet up... Why did it take a third party to start doing it?
http://blog.priceonomics.com/post/30393216796/what-happens-t...
TLDR; with bikes theives can hit a sweet spot in the trade-off between risk and reward.
It seems more like the case that he's taken on the overhead of investigating and coordinating meetups. Once that's done, the police seem happy to do the actual arrest.
However, this sounds like there are some very bad incentives in the PD, where performing arrests is prioritized over investigation. However, I think characterizing the issue as "simply do not care about bike thefts" may not be the most accurate description of the problem.
The police force can only really enforce the law because society gives them permission to do so. The instant that you have mobs of Bike Batmans the police will act because now you have increased vigilantism - and people taking the law into their own hands.
This sort of thing can escalate very quickly. If bike batman works well, then why not murderer batman, or rapist batman? And then there is the escalation of enforcement. What if bike batman decided to really get serious and use a gun to get the bike back?
The point is that the police should be handling this!
Laws are an excuse to be able to target kinds of activity the government wants to target at the time; it's more "laws enabling cops" than "cops enforcing laws".
That's why drug laws are so handy; all you have to do is say "I smelled marijuana" and you get to throw in jail whichever problem population you're targeting at the moment.
This way, the community are the ones initiating police action, rather than the police themselves (which, as you point out, bad incentives can then result in an unhealthy relationship between the community and police).
The problem is that it is probably rare that police is even willing to spend 30 minutes on traveling to a known location for a stolen bike. Seattle (maybe the US in general I don't know) seems like a good place in this regard if he isn't laughed at when trying to get a police officer to come talk to a bike thief.
From what I can tell, the police are good people, but the DA's are generally useless and are only interested in pushing an alternative social agenda as opposed to enforcing the laws passed by previous generations.
I mean, it sure fits the evidence. No one has an interest in "enforcing laws", they're tools to exert the power they wish to exert. In SF, I guess that's balancing property values that give you the cash to run further political campaigns with the social agenda shit that they think gets votes.
Police don't really have independent priorities beyond "paychecks & cool shit with minimal accountability" (in fairness, basically the same priorities as any other job, especially government jobs). They are mostly the penultimate shelf on which shit, rolling downhill, rests (the public gets to be the final one).