Very many people have small businesses and if we use the car for business it can be depreciated for reducing our taxes.
Same in Poland and everywhere else in Europe. So it doesn't affect the statistics by much.
So these cars arnt considered into the passenger car total but instead into the commercial total.
Exactly. The cars used for commercial purposes aren't considered into the passeger car total in the U.S., Europe, Poland, and everywhere else. That's why in the category of passenger cars Poland is ahead of the U.S., but in the category of total car ownership (including commercial vehicles) the U.S. is ahead o Poland. Americans have more cars, but Poles have more passenger cars. Ownership of passenger cars in the U.S. is declining, while in Poland is growing.
So for a family of three we have six vehicles. This situation is not unusual.
It may not be unusual where you live. But it's something unheard of in New York City where 54% of housholds do not own a single car. In Manhattan 77%.
Our cities have great transportation...
Sorry, but you must be joking. Have you ever been to Europe? Compared to EU American public transportation is dismal:
New York City has relatively good public transportation - true. But subway sucks compared to most metros in Europe. It's old, noisy, expensive, breaks down constantly, and kills people (55 deaths last year).