I live in Clearwater (Tampa Bay area). I have to say, while I see a lot of new and re-worked roads adding bike lanes, and more signs in places saying "Share the Road" with a bike symbol, I still pretty much avoid road riding for many of the reasons stated here by others.
I am a native and unlike some posters, I do love a lot about my state, but it is NOT bike friendly (barring the Keys). Of course, since a huge amount of folks who live here came from up north, I wonder if their bad manners towards bikers came with them! Seriously, I think others are correct. we have a sprawling car-based infrastructure, with a lot of people doing other things than paying attention as they commute everywhere. Until recently few areas around me saw many if any bikes on the roads. They are doing a lot with adding signs bike lanes, and trails, but the driving population here has not "gotten the message" that bikes are out on the roads.
I do see the advocacy moves improving things and I do see more cyclists on the roads now a days, but on a recent rare road ride, I passed two different people riding the wrong way (facing traffic) down the bike lanes I was on and I see that ALL THE TIME on the new bike lanes everywhere. So barring those who are more serious cyclists and rec. riders, there may be a lot of folks on bikes around here who don't have any understanding of proper road rules as cyclists. I'm sure they don't help either. So combine some ignorant cyclists with a LOT of ignorant (and inattentive) drivers, lost tourists and little old folks who just renewed their license by mail for another 15 years and it's a bad mix.
I do feel blessed that we have a fairly aggressive "Rails to Trails" program here. I stick mainly to those trails, especially the Pinellas Trail and the Suncoast Parkway Trail. And more are connecting and spanning the various counties all the time! Still sometimes I fantasize what it'd be like to live in a truly bike-friendly state. I guess it's good that I don't fully know what I'm missing!