Having been involved in this on the dibble side, one of the biggest problems is the dearth of evidence in most cases.
At best there may be CCTV, but if it doesn't show a clear view of Johnny Scumbag's face it is of no use whatsoever in a PACE compliant identification.
Witnesses are great, but only if they a) know the offender, b) and are willing to appear in court to confirm that identification. Quite often a witness, or someone who has seen Johnny Scumbag's picture in the local paper, will tell the police a name - that name is useless on its own unless they are willing to give a statement and appear in court, which most witnesses are not.
Of course, if the same name keeps coming up then you start to develop grounds for a warrant, but Johnny will have sold it on pretty quick to buy himself some goofballs, so warrants in pursuit of stolen bikes rarely bring paydirt.
And then the owners themselves don't help. Most don't keep a record of the frame numnber. Some will say something to the effect of they can identify the bike because of some unique accessory or scratches, etc, but if they cannot evidence that with a photo or other documentation it's only heresay, one persons word against another and that is insufficient for any purpose.
It's easy politicians to whittle, but where is their solution to the problem, and why did that paticular gang not address it the five years they were in joint government if it bothers them so much? That's as far as I'll go with that one - suffice to say I'd be interested in hearing of some solutions that are realistic and affordable instead of cheap point scoring in the lead up to a big vote.