The important issue is that R&D spending is not a good measure of outcomes. A lot of R&D spending goes to high administrative salaries, equipment, facilities (real estate), and related costs that do not translate into outcomes.
What would you propose as a better metric of innovation?
I don't think there's a single perfect measure but if you put it in broader context of measures like Nobel prizes R&D spending, patents, etc. it does seem to paint the picture that the US disproportionately contributes to medical innovation.
It's very similar to the measure of health. There is no single great metric. Using a single metric like BMI or blood pressure is flawed. However, you can get a clearer picture if you bring together multiple metrics.
