I think that actually is partially the reason, but I think there are many others. In this case, it's simply because pinball never really caught on in any non-white country. That means that for someone who immigrated to the United States or Europe, or who had parents who immigrated to the United States or Europe (like me), they probably didn't grow up with pinball. Certainly, I didn't, because my parents associated almost exclusively with other people of their culture and knew comparatively little about American culture. Hence, I had a harder time understanding pinball, and I pretty much had to force myself to understand it.
(I actually didn't learn until long after I graduated from college that the respectful thing to do when given a gift or offered food is to accept it, for instance. In my parents' culture, that is considered highly rude, because if you do so, you are viewed as greedy and taking advantage of other people's generosity. The polite thing to do is to always turn down any gifts or offers, and this is what I had been trained to do. Even now, I am trying hard to unlearn it, but old habits die hard.)
As one such "person of color," I can say this: Just do what you've always been doing. If you are aiming to be as inclusive as possible, aiming for an ethnically diverse player base, it will eventually happen. It might take many years, but it will happen. The problem currently is lack of familiarity by these other cultures.
That being said, bars tend to serve a specific group of people. The nearest bar to where I live, for instance, is targeted squarely at local Hispanics, with Spanish-language sports on the TVs (especially fútbol) while serving Modelo and Corona. I have never seen a general all-inclusive bar that isn't also something else, a la Buffalo Wild Wings or Dave & Buster's. (That bar's location is across the street from a taquería that has a World Cup Soccer (1994) inside of it that earns well though.)
Putting them in diverse neighborhoods, or in neighborhoods with a non-western community, doesn't always work. 82, Los Angeles's biggest pinball place, is across the street from Little Tokyo, but the locals ignore and avoid it.
I think a better solution, actually, is to put pinball in places other than bars. Each individual bar has a very specific clientele, typically consisting of middle-aged people or older (and mostly men). Odds are if there are people from other cultures, they're not likely to try something new. You can't teach an old dog new tricks. Rather, I would suggest putting these machines up in places where kids hang out. They are far more receptive to unfamiliar things, far more curious about unfamiliar things, and, if they are the children of immigrant parents (or children of parents who stay within their cultural bubble their whole lives), are far more in tune with western culture than their parents are.
These kids are an audience right here, and if you can get ethnically diverse children playing pinball, they will become an ethnically diverse community of adults before long. It will definitely be hard to pry them from the myriad of entertainment options they already have, but personally, it's still easier than trying to pry attention from someone who grew up having never heard of pinball.
My personal thoughts: The local communities are welcoming. The fellow local players are not the problem though. I cannot sustain a conversation about pinball with anyone else of my parents' culture regardless of their age because I will just confuse them. I cannot bring them to any pinball location because the lack of familiarity with pinball intimidates them. (You know, the invent-an-excuse-to-not-go kind of response.)