Might have, at some point.
I think part of it is that officers aren't informed of what the law is. Hell, even the Sheriff wasn't aware of the supreme court ruling when I talked to him, and he's a big NRA buff. (It was all over their news back in 2009, dunno how he could have missed it.. but whatever).
It's sad, but I've had several friends arrested at one time or another for UUW. One was carrying a gun in the cab of a pickup truck, in a case, unloaded, and STILL got arrested for it. Cop said it was "immediately accessible", if I recall correctly, despite it being carried legally.
As far as false arrest, you can sue if they detain you without probable cause or arrest you for something when you're not in violation of a statute. But it costs $$$, and chances are, you won't win.
I fought a traffic ticket for 6 months once, and lost. Cops "lost" the video evidence they submitted, kept getting rescheduled over, and over, and over again. Would show up, spend 8 hours sitting there, then at the end of the day kept getting told "we couldn't get a jury together today, you're going to have to come back." It would have been cut & dry to a jury; I was cited for "failure to yield to an authorized emergency vehicle". The video would have clearly showed me COMPLETELY off the roadway.
(I know they had video, because they delivered the ticket to my office *3 days* after the event transpired).
After 6 months of going to court, and 40 hours of lost work, I showed up 8 minutes late (was held up at the x-ray). Came upstairs to the traffic court and the assistant States Attorney was waiting for me with a big old smile on his face. In those 8 minutes that I was held up by security getting fondled, they had my trial and found me guilty in absence.
Yup, that's Illinois.