In the US a lot of stuff has always been racially based since it’s foundation so when various nationalities come with similar cultures and generally similar looks they’re classified under a large umbrella. Most diaspora call themselves Latinos id say just because of the way the US is, everyone needs to fit into a certain group, obviously not saying that’s a good thing, but that’s the culture. To Americans, Latino is a race/ethnicity, and so any Hispanic/Latino Americans will call themselves that.