Farmers deal with pollination issues every day. Drug weed farmers need to learn to do it too.
Hemp will be the major crop in terms of acres planted. It won't take many acres of drug weed to fill the recreational and medical demand.
I'm running a little experiment this summer to explore just how difficult an issue controlling hemp pollen really is.
Your analogy to other farmers is flawed.
Farmers of other crops generally don't care what pollinates their crops, because they are selling the fruit, which either has seeds anyway or is a seedless cultivar that won't grow seeds even if pollinated. Either that, or they are selling the leaves/stalks/roots, in which case pollination is also irrelevant. With drug cannabis, we very much care that NOTHING pollinates our crop because all we want is unpollinated fruit. Unless we are breeding, in which case we isolate the females to ensure we know where the pollen came from.
In that sense, we are like the breeders of seed for other crops. And those people have very strict protocols about how far different cultivars are from each other to make sure they know where the pollen comes from. And for the big commercial crops (e.g., wheat, soybeans, corn), the seeds produced go through a strict testing and certification program (usually by the local state agricultural university) to ensure that their seed is unsullied by random unknown pollen.
In other words, farmers of other crops either (a) don't care if their plants are pollinated by junk; or (b) care very much and have to take rigorous steps to control it.
If you happen to live downwind of a large commercial hemp operation, you can forget about an outdoor grow, and you'd better seal your doors and windows if you want to grow indoors.