In the sources that I've seen, the difference in interest rates between the US and other developed countries seem to be off by a more-or-less constant differenc

In the sources that I've seen, the difference in interest rates between the US and other developed countries seem to be off by a more-or-less constant difference. This difference seems to hold historically. This suggests that the differences are largely influenced by differences in measurement between countries, or by other pre-existing policies. (I'm far more partial to the idea of divergent measurements, because I'd have expect prices to become wildly different over time, but that doesn't seem to have happened.)