As far as I remember, even since the 90s, mostly European teams were racing in F1.
Is there any specific reason? Or is it just that Americans do not care about F1 because they have IndyCar, drag races and so forth?
I don't believe it is financial reasons, but what about technical reasons? Is it too complex to build a new car from scratch?
I think (but I am not sure) that it is for historic reasons.
America has a long history with Indy Racing League, Champ Car, Nascar, drag races, and so on, so most American people follow these races instead of Formula One.
So it is probably a choice taken after a cost-benefit analysis.
However, in 2010 there was an unlucky US team that tried this adventure: US F1.
A group of capable Americans with extensive experience working in F1 garages and factories absolutely could have the necessary technical capabilities to develop and build a Formula One Car from scratch like all of the other teams on the grid, but there's a simple reason why we don't see many F1 teams that are exclusively American in identity (although Haas has recently broken the trend, and has a competitive package, although they are closely partnered with Ferrari and buy as many Ferrari manufactured parts as the rules will allow). The reason there have been very few American F1 teams is because of the lack of exposure and interest for the series in America. America has a rich history of competitive motorsport, but it has been almost entirely in formats like NASCAR, IndyCar, and dirt track racing.
Running and maintaining a Formula One team is exorbitantly expensive, and so each team on the grid must rely heavily on lucrative endorsements, sponsorship deals, and partnerships with engine and automotive manufacturers to develop a competitive race car anew each year. Traditional F1 teams headquartered largely in the UK and Italy can command hugely prosperous deals because the viewership numbers and consumer engagement with the sport is exceptional, and in turn provides investors and business partners with means to have their message reach a burgeoning global customer base.
Simply put, potential American Formula One teams cannot raise enough money through the traditional mechanisms of procuring investment capital and sponsorship deals to be able to develop a competitive race car, which exacerbates the same problem in further years until the team in completely insolvent.
A few caveats before I go. In my answer I was envisioning an "American Formula One" team as a team that readily and openly identifies itself as an American team and that has the majority of its facilities located in The United States, including its Headquarters and the bulk of its manufacturing facilities.
I mention this caveat because we could imagine a case where Dieter Mateschitz gifts Red Bull Racing to one of his close friend's sons whom he acted as Godfather for, and that after a few weeks of the close friend's son firing long-term employees and replacing them with his good friends from The States you could justifiably consider Red Bull Racing to then be an "American Formula One Team", which I think we can agree that it would most certainly in fact not.
