Its not just American tourists
I read that France, home of snooty cooking traditions, is actually McDonald's best market per capita, even more so than America.
The restaurants are well-lit and clean, the "food" is cheap and rapidly available and the quality is consistent. It is something of a marvel of modern management. Also, you have to ask why other countries with more ancient food traditions haven't been able to pull off a similar worldwide brand.
(And sausage Mcmuffins with egg are almost diabolially good)