“...There is simply NO monopoly in the pharmaceutical industry...”
Perhaps I shouldn’t describe the constraints on my access to lower cost medicine as a monopoly. So, instead of “monopoly”, you can choose a more appropriate descriptor for the reason I can’t legally buy prescription pharmaceuticals internationally and avoid paying big-pharma’s rates.
It's called a 'patent'. US laws prevent importing of patented drugs. You have to understand that the production cost of most drugs is near zero. Almost all of the cost is in the FDA approval process. US drug manufacturers must price their products to recover that cost, as well as the costs of drugs that are not approved. They can also make a little profit from selling their products in price controlled countries outside the US. These prices are far below what the price would need to be to recover their FDA approval costs. So they price their drugs in the US to recover their US approval costs, and they price their products in other countries to make a little profit. Allowing reimportation of these drugs would eliminate the chance of recovering their FDA approval costs.
Once the patent expires (which is usually only a few years after the FDA approval is granted), all this goes away, because the FDA approval process also requires them to tell exactly how they make the drugs, so anyone can make them once the patent expires.