I think the fact that those two countries are called out as an example suggests that monthly is not the norm; difference exists, but common discussion/compariso

I think the fact that those two countries are called out as an example suggests that monthly is not the norm; difference exists, but common discussion/comparisons tend to use hourly (as shown in the top table), and the majority (?) of countries do as well. At the very, very least, it's not a uniquely American thing.