This is a commonly cited reason but I don't buy it. They're selling these things for 4 cents in tanzania so we're talking about something that is practically free to make. There are lots of things that cheap where we see competition in the US: paperclips, reams of paper, chewing gum, whatever.
Why is there competition for these things but not cheap drugs?
Situations like these should count as evidence that something isn't quite as it should be.
Is there a chemist in the house? :)
Look for the explanation by Derek Lowe in the linked article. Key points:
> The FDA grants market exclusivity to companies that are willing to take ‘grandfathered’ compounds into compliance with their current regulatory framework.” Once a company does that, it gains an effective monopoly through the "generic bioequivalence" rules.
Setting up the production line isn't the issue, because the pharmaceutical company will outsource the actual manufacturing of the drugs anyway.