Montana is only one of a few states - numbers range from 3-4 - that has a registration law with established sites and 3 mile buffer zones.
Whereas comments from NY and TX blame commercial beekeepers for objecting to registered sites, the Montana State Beekeeping Association is almost entirely made up of commercial beekeepers. They, as an association, work hard to provide adequate funding to cover the costs of a State Apiculturist, even going so far as helping adjust the fees to provide adequate resources to the state to cover inspection costs. Since hobbyists aren't required to register, the costs to commercial beekeepers are self-imposed.
Gene is correct about the economics. The 3 mile buffer zones were originally set up to protect bee health. It adds value when a MT beekeeper decides to sell an operation with registered sites.
After use of antibiotics became common, the health argument in MT weakened, until the problems of 2006-2010. During that period, very few of our beekeepers sustained any major collapsing problems. Those few that experienced it had major losses. But, in MT, we saw no evidence of transfer of whatever was going on, crossing over from neighboring commercial operations. We did a lot of sampling and analyses. Those few commercial beekeepers who had problems generally reported having seen problems in their neighboring commercial operations while in CA. At least one major Montana operation decided not to migrate, and they've been doing fine ever since. These days, I'm convinced that the spacing does protect bee health. It reduces transfer of contagious problems, including mites.
From our bee training and flight to target trials, I have data that re-affirms spacing effects. Bees readily and quickly fly 1 mile. Any state considering a 1 mile buffer should just forget about it. To a bee, that's not a significant distance.
In urban settings, numbers of bees from a source apiary, arriving at the target site two miles away, was still strong, but the bees were beginning to show a drop-off trend, with fewer of the marked bees arriving from the source apiary, and more interloper bees arriving from backyard beeyards, as well as a commercial beeyard about 1/2 mile from our registered, source apiary. This 1/2 mile spacing was lawful, because the source site was a landowner site. At 3 miles, zero or a few bees arrived from the source when nectar resources were abundant.
Jo Traynor summarized older studies in one of his articles. I'd have to concur with the argument that at about 4-5 miles, bees probably use as much energy as they expend, can only go that far if that stop for snacks along the way. Records show marked bees as far as 8-13 miles. I assume that's either only when nectar and pollen resources are very scant or the bee got lost. When we flew bees from a boat in the Gulf off of the FL coast, most of the bees foraged on the land, but one landed on a boat a mile out to sea. If bees can be happy, that one was.
Bottom line, very few states still have registered sites and spacing buffer zones. Those that still do have to work to maintain that system.
In MT, the benefits are self-evident to the resident commercial beekeepers, so they as a group support the Bee Act and the Inspection service. Commercial beekeepers looking to establish in MT fall into two groups. Some, who turned out for hearings that last time the State law came up for discussion in the Legislature, tend to be young families looking to establish in a state where over-crowding with bees doesn't jeopardize honey crops and bee health. They consider the MT Act to be an economic and sustainability benefit. The long-term odds are better that they may have a business to turn over to their kids. The other group are a few commercial beekeepers who keep trying to wedge themselves into MT and really want the MT State Act to go away so they can bully their way into locations.