Our country is so big and heavily populated (and most of our many, many populated areas are overshadowed by a few really touristy places like New York, the Disney parks and Yellowstone National Park and Hawaii which isn’t even that American) and that you’ll rarely encounter someone from a country that uses the 24 hour system. Canada uses the 12-hour clock if I remember correctly from when I last went there, and I think Mexico does since we usually learn their dialect of Spanish in school (but I’m not sure, in all my spanish classes they taught us to say “son las ocho y media en la noche” for 8:30 PM, instead of “veinte y media horas” as I was taught when I studied in Spain for a semester)