Not taxes, but having to meet American emission & safety standards.
When these kinds of vehicles sell elsewhere in the world for such low prices, it's because they do not have to meet the stringent emission and safety standards that all cars sold here must exceed. The air quality in the places you traditionally find these kind of vehicles is horrendous.
I say this not as an argument against clean air or safety; Just as a reminder that such benefits do come at a cost and it's useful to know what those costs are.