- Limited to no local feeder series. NASCAR is the local product, with open-wheelers some distance back from sports-car series (which is a bit more down-to-earth in terms of expenses).
- Terrible TV Times. More than half of America is either asleep or getting ready for church at 8:00-10:00 Eastern Time (even earlier for Central, Mountain, and Pacific time zones), so ratings are always going to be middling. And that's if the races are on The Continent; ratings for a race in Japan or China are very limited to the hardcore fans, unless they're on tape delay.
That said, there's been an uptick in American interest and ratings, but it's probably always going to be a niche sport. Usually folks who take an interest in cars or have a career in the field are much more likely to have exposure and interest in F1, in various degrees, than someone who isn't. Auto racing has a bit of a stigma that "it isn't a sport" so it's discounted a bit in areas with century-old sports franchises. It's also a "rich man's sport", so poorer classes or hard-scrabble areas of the country can't really relate to the problems of a million-dollar vehicle that's a half-second off the pace.
Having a team and sponsors get heavily involved would help, but see my first point. Companies aren't typically going spread themselves that thin; there's always a few American sponsors and that hasn't changed much. It's still a ginormous economic engine, a tremendous population base with a very large middle and upper class, so it's almost always a target for growth. But we're also people with many sporting interests; besides the pro teams (nearly everyone is a fan of at least two pro sports teams), there's usually a college sport that's popular too; also, there's golf, hunting, fishing, tennis, and their kids' sporting activities that might take precedence. At some point, the fan isn't going have much time for another highly-technical pastime, unless they're also a truly dedicated sports fan with limited to no other interests; although in that case, those 7am starts have limited competition on the dial.
