And then she'll turn around and re-invoice us for the base use at places like Landstuhl Regional Medical Center and the Ramstein Air Base. How many tens of thousands of our injured soldiers have been treated at Landstuhl and how many hundreds of thousands of flights have we staged from Ramstein? (and that's just the tip of the iceberg).
Our NATO treaty is a lot more complicated that just writing a check (write a check to who by the way?) It is a treaty that involves mutually sharing assets and resources. Some nations like Germany may not write as many checks because they are hosting a lot of NATO partners in their country and offering up a lot of their resources to it.
Especially so when Germany is both a key medical center and midway point to the ME.