This is not quite true yet. In the USA, approximately 239 million people speak English at Home, while only 42 million people speak Spamish at home in the USA. And while that number is still rapidly growing, there are 5.69 times as many people speaking English as their primary language right now, so it is still extremely dominant. Though there are localizations where Spanish or other languages are dominant (just not the USA as a whole).
That’s not to minimize anything. 42 Million is still a HUGE number of people, and from a business perspective, they are likely to earn more money and market share if they make their stuff compatible for those people who have a different language preference. So the main question from a business perspective is whether the small amount of work to be compatible with language settings is worth the bigger market access they will gain from it. Considering Spanish could bring access to several million more people, it sure seems like a good idea to me.