According to them, the other developed countries that have negotiated lower rates for drugs serve a different purpose. Those countries have lower requirements around testing of drugs and medical devices, and they are able to move to human trials and market sooner there. The trade-off for those countries is slightly higher risk of sub-optimal outcomes, but this appears to be more accepted by the populations of those countries than it is by Americans.
I'm not writing this to vouch for this setup - it seems like it is pretty unbalanced and ultimately does a lot of harm to people in the US due to drug inaccessibility - but I thought I'd share it for another perspective.