I am also about 300 feet from an apiary. I agree that honeybees seldom if ever visit my tobacco blossoms, although I have seen bumblebees occasionally visit them. My guess is that most bees prefer the wildflowers that fill the intervening pasture. Chillardbee has documented his honeybees foraging on his tobacco blossoms. So if tobacco pollen is mostly what's available at a given time in a given location, that's where the bees will forage. Bees seem to perform an uncanny calculation of preference vs. distance.
The difficulty of the issue is that bees (wild or domesticated) don't drop dead by the hundreds around the blossoms of plants treated with neonicotinoid insecticides. The effect of pollen foraging seems to be an incremental increase in the risk of hive failure. If that were the only threat, it might make little difference overall. But the scores of different pesticides that are used at an ever increasing pace on all sorts of plants, especially in multi-acre monocultures--well, it all adds up. There's no free lunch.
Bob