To answer your question: The INVENTION RIGHTS ran out a long time ago. That’s why it is generic.
But, the DISTRIBUTION RIGHTS in America is a legal trick that the lawyers (and legislators) constructed to throw a very lucrative bone to this company.
I don’t know enough to understand exactly how they did this. But, I have been guessing that the FDA with their power, rules and regulations have some how made this possible. A post above came very close to touching on the explanation. Someone in the past administration may have tried to set-up a backdoor tax on the American people to subsidize poor countries in the world through the UN. Or alternatively, some legislators got a kick back. Or alternatively again, the distribution company just has some VERY GOOD LAWYERS to benefit the company exclusively.
The “Albenza” brand name drug has “distribution rights” contracts with their distributers...generic Albendazole has no such contracts. Anyone can manufacture and distribute it if they wanted to. (Like Glaxo-SK did with the million doses for 3rd world countries). See my post #48.