one ever checks for it. It is an FCC requirement. The FAA in the United
States and its corresponding agencies in other countries do not feel it is
their responsibility to enforce FCC rules. Neither do the different
countries' customs and immigration agencies. And the radio licensing

Assume that if you're ramp-checked in Germany with a N-reg aircraft they
*will* ask for the radio station license (and your radio operator permit as
well). It's a) cultural and b) N-reg planes go around some certification
req's in Europe, so there is a "case" ...