Bees in general didn't seem to have so many issues before raising food became corporate megafarming. Family farms typically raise a variety of products in a smaller acreage, and the bees had a variety of nectars to sample, plus they had a season to rest.

Highly hybridized high cropping plants may also produce less nutritious nectars, just as many of the most beautiful roses have almost no scent. The bees burn a lot of energy while gathering nectar and pollinating in the process. If I had to work hard and starve while doing it, I'd find a new job too.