Isn’t the solution then to build a national infrastructure for late stage trials as opposed to putting life-saving drugs behind a ludicrous paywall, whose price is determined by the opaque malfeasance of the healthcare system in the US?

Late-stage trials are enormously costly and negative results are common. To publicly fund them, we'd have to be ok with governments spending billions and getting nothing for it. And after the fact there'd be a long line of people saying how $treatment was obviously never going to work and only an idiot would ever have let it go forward for stage 3 trials.

I'm not opposed to the idea, but I think you'd struggle to make it politically achievable.