It was written in invisible ink then, obviously.

Well they aren't going home though are they? and they don't really seem to care either. So it's happening and most likely because the rules are so convoluted. It'll probably continue to happen as well, and I don't think all the thieves mean to do it in any malicious way, they are just trying to roleplay a thief.

Some rules consistantly get broken because they don't work or seem pointless or are overly complicated. A GOOD EXAMPLE would be the yellow bag rule itself. Lots of people don't bother carrying one (which hey, has a big impact on thieves oddly enough, and is probably a big contributor to the above problem), and no matter how much people go "HEY GUYZ, CARRY A BAG PLZ" they still don't do it (and it's hardly suprising either, but that's another point entirely) and they won't do it. Even though it comes up every other month, a large number of people don't follow the rule.

As the yellow bag rule (which like half the community doesn't follow) has a big impact on thieving, the thieving rules could go a similar way (btw I mean people just stealing mundane items out of packs and stuff, not camping people at the bank for omgarties), or you could end up with no thieves at all. Well thieves that actually steal that is.

So something is broken. What are you* gonna do about it?

You can try the shouting at people generally on the forum going "FOLLOW THE RULEZ YE DAMN SWINEZ" but that isn't really working as we have witnessed many times before.
You can go after any thief that doesn't follow procedure and have them BANNED or kicked from their guild or whatever, but I'm betting that'll just result in no thieves at all.
You could go after the non-bag carrying bunch as well, but they'll probably just ignore/laugh at you, as you can't realistically defeat the hordes of anti-baggers. I mean what'll it be, auto-ban anyone not carrying a yellow bag or something?
You could try looking at the root of the problem and fixing it (like, letting a thief steal any mundane item in a persons pack or something), but considering how long it takes for people to agree on anything that involves changing a rule, it's not looking likely.

Or you can do nothing! In which case think of threads like this as a way to occupy your time. I do. =P

* You is being used in the collective sense here.