Van, my best VSH girl's crew are great mite biters. So are her daughters. Powdered sugar rolls are 1 or 2 mites per 1/2 cup of bees. Even if I'm off by 300%...not a bad count. Way lower than the bee club bees that were bred from treated stock.
I'm not sure what the special circumstances are in the Florida Panhandle, but more than half of the beeks I know here are chemical free. It isn't that I've never seen mites. Maybe what helps (in part) is:
1. Hot summers. There's some thought that mites don't lay so much when heat index is over 100. Of course neither do queen bees, so maybe there's a brood break.
2. LOTS of feral colonies around. Meaning, feral drones from survivor stock are fathering the progeny in splits.
3. Some beeks do feral cutouts, then sell those bees, which are then are "domesticated" and split.
4. The biggest commercial op is 30 miles away. Maybe their mites stay up there with 'em.
5. Non-treatment beeks with 10-80 hives use screened bottom boards.
6. Palmettos, anoles, and even some brown scorpions are around to eat up mites that fall out of SBBs.
7. Many non-treatment beeks are foundationless (ref: the "small cell" theory).
8. People say, they lose a few colonies with chemicals, and they lose a few without chemicals. "Might as well save the $$$ on chemicals." (Notice this is not an "eco/green" choice - it's a choice to save the greenbacks, LOL.)