If a medicine is approved by the FDA for a use in the USA, it was required to prove it works for that use. Many would argue that if anything the FDA is too restrictive by international standards. For example, the AstroZeneca vaccine remains "illegal" here, even though we bought enough to vaccinate the entire population.
Some might argue that "better" of course cost more, but "better" is a pretty broad term, So I won't make that argument.
It could probably be more directly argued that the high US health care cost subsidize cheap health care around the world, as international medical companies know the US market will pay for them to develop new treatments. And products that have already had their development costs paid can be sold to more cost conscience markets, as the per item production costs are low. Sort of like the movie industries reasoning behind DVD region coding but at the national level. The market of 10k people willing to spend $10 are not going to have as much impact on a product as a market 100K willing to spend $100, but if production only costs $2 it is going to be available to them for $10 eventually.