Why isn't there more american masked wrestlers?
I mean, masks are cool , they make good merch, and if you're ugly, solves that issue right there.
It's a multi-layered issue in my mind, so I apologise for the rant.
First and foremost, it's not just an American issue, it is a Western issue. Because whenever someone decides to don a mask, they fall into one of two traps. Either they become a parody/comedy relief act (Hurricane, Curry Man, Kendo Nagasaki) or become low-rent Great Muta and reserve it as a "demonic alt personality" like some edgy kid talking about his wolf spirit form on tumblr. Amusingly both Jonathan Gresham and TJP are both doing said act. Whereas Blake Christian has opt for the body paint approach instead like Finn Balor.
Next comes cost and personal investment. For a Mexican looking to get into wrestling in his country, the quality and range of mask makers is fairly high. Thus he can revaluate his options at a local price. "Deon Sparks" (who shall be our hypothetical indie wrestler) has been hustling on the circuit for the last seven months after spending close to year in wrestling school. Deon ain't got shit to his name in terms of rep nor a dime. So he has to make a choice when it comes to his gear. Does he go and get himself some cheap trunks and boots from Highspots? Maybe get some funky jeggings from Hot Topic and rock his sneakers, keep those dollars set aside for gas. Or does Deon pray that he can find a basic mask/singlet combo that fits? Because you know for a fact that anyone who specialises in head gear, that shit is custom fit and thus costly for just about anyone not being booked for a super indie biweekly. And by the time Mr. Sparks is getting attention, will he throw aside said booking chances because he can now afford a mask? No.
You want a great example of someone who attempted a mask on the indies early on and looked shit? Fuego Del Sol. I love his promo game, amazing seller. But his first six months in AEW, that mask would loosen itself every other move. Now he's a small guy, hell he's basically Mexican. Deon has a nigger sized head. He ain't getting a mask that fits that isn't a balaclava or custom made.
Another thing to factor in is overviewing what companies want! WWE has often stressed the importance of emotion, which is best expressed facially. It's a big reason why they got Andrade unmasked prior to joining NXT and why Sami is well, Sami. It's rare to find a company willing to accept a Westerner in a mask. Those that have masked Westerners, well, look at how they are positioned. Evil Uno and Serpentico are enhancement talent in AEW. Axiom, despite being one half of the NXT tag-team champions; is the comedic relief to Nathan Frazer. I'd argue the best example on the indies and touring circuit right now is Ninja Mack and sadly you can argue he started out within the first category; parody. Hell the Wyatt Six would be more terrifying if they wrestled with masks, but they don't. Second the bell rings, it's just three dudes who look like they have Discord kittens rather than demonic plans.
Japan is the only other place that seemingly attempts masks, but even than they become isolated concepts. TJPW has multiple girls who are completely separate wrestlers/gimmicks when masked. Enhancement talent also get masked up in the hopes that the green rookie, once ready, can be something and thus, show his/her face.