> but it doesn't explain where they come from.
Sure it does. They come from the Internet, it explicitly stated that.
Joking aside, from my understanding, the issue with bees is a combination of multiple factors, such as pesticides, disease, parasites, etc.
Those are primarily local issues. So it's perfectly feasible to find some isolated spot in the US, grow a ton of bees, and ship them across the country to wherever they are needed to make up for any local losses.
We can easily engineer around this issue, by increasing the bee population, genetically engineering them to be more resistant, wipe out parasites, or change the formulation of pesticides. It seems the market is responding by simply growing more bees to make up for the losses, which should be a viable solution in the short-term.