Since horses evolved in North America and lived here for more than 50M years, only going extinct about 10,000 years ago, it can at the least be argued that their introduction is really a reintroduction. Especially since there is some evidence that their extinction here was partially due to human action.
LOL
Remnds me of that old WWII ditty
“We did it before and we can do it again”.....
MAybe they were wiped by by global warming / cooling or the like?