In my experience, most of the boats passing under the small bridge are either small fishing boats or small pleasure boats. They are mostly slow boats that are taking a short cut to Peanut Island or the inlet. The bigger, faster boats generally have no problem going around the park & under the big bridge. For the slow little boats, going the long way around can add a fair amount of time, & if someone is looking to be set up on a fishing hole before a current change, the difference can be a deal breaker on the bite. ...then there are also the people who just don't know, or to put it more politely, lack local knowledge. Some people who put in at the ramps there, have no idea that there is a dive haven right next to them. Also, in Florida, there are few rules concerning who can drive a boat. The requirements for knowing the COLREGS (rules of the road) and proper boat handling skills are quite sparse. The skills & knowledge bases of the "captains" out there, varies quite a bit.I understand what your saying, however, if an area is filled with dive flags, IMHO then no approach to the area is reasonable. Not sure if this is a good analogy, but imagine people in a crosswalk but they are crossing against the light, that doesn't give drivers the right to ignore them and run over them. I see this on the westside on the section south of the big bridge, and either north or east of the channel. Occasionally boats come in there when there are a bunch of dive flags scattered about, any boat leaving the channel entering that area while dive flags are about, is not making a reasonable effort to avoid dive flags by 100 feet never mind 300ft. Many of them are divers which makes it even worse. They just don't care, if you are in their way to bad. I understand people wanting to use a boat at BHB for night dives, or when the ocean has five foot swells, but why dive there on a boat when the ocean is nice? One of the major attractions of BHB is you don't need a boat to dive it.
As for me, I try pretty hard to avoid getting close to dive flags, unless they are on some boat that is parked at the sand bar & just has the flag up (illegally) as a status symbol. Not all of the other "captains" out there really know what to do when they see the flags. Occasionally, I come across public service announcements about the dive flag rules. There should probably be more of them. More signs should probably be posted at the boat ramps, especially that particular boat ramp. The guys who fly the dive flag when divers are not in the water should probably get their wrists slapped a little more often too.
The only time I've dove BHB from a boat is when I was anchored up near there to overnight. That's not very often.