For locals, the area has a much higher % of fly fisherman than most. On account of having so many good streams, there are many avid fishermen. And avid fishermen are more likely to cross over to fly gear than those that fish a few weekends a year.
For out of towners, it's a world famous fly fishing destination, and avid fly fishermen are willing to travel to fish such places.
So it's not a suprise that fly fishermen are over represented even though regulations don't demand it.
And to be honest, in the TT section, I see about half and half in the early season. More fly guys as you approach late May (many of them may be the same fishermen, switching tactics as the season wears on).
The ALO section is mostly fly guys. But that's to be expected, bait is much more popular than hardware, and there is plenty of good, bait friendly water around that they don't have to resort to hardware to fish good water.