I still find it frustrating to see the exact same vehicles get significantly different tow ratings here vs Europe.
The other day the dealer tried to warn not to tow my utility trailer with my car as it would hurt the transmission (trailer was empty by the way). I pulled up an article from the UK where it was in the top three of best towing cars for this year.
Dealer looked at me like his brain needed to reboot, after which he told me the cars in Europe must be built differently or get different transmissions and left it at that.
It's truly baffling that manufacturers here hold that towing capacity hostage for arbitrary reasons.
There might actually be technical reasons for this.
E. g. top speed in Europe while towing is 100 km/h (some countries and trailers less), whereas in the US you can drive up to the designated speed limit.
Bearing load is also different, in Europe it's usually 4 % of the trailer weight, in the US at least 10 % is recommended.
Trailers are also different, e. g. unbraked trailers only exist up to 750 kg in Europe, whereas in the US I've seen much heavier trailers without brakes.
Trailer brakes are also different, Europe uses overrun brakes, the US electronic brakes.
I've never heard the term "overrun brakes" (TIL!) before. I've always called them surge brakes, and they are widespread in the U.S. on the majority of boat trailers.
That's actually the most reasonable explanation I've seen so far, and it helps explain a bunch (one small correction: most states have a towing speed limit of either 55 or 65 mph, so just about the same or slower than in Europe. Canada is even worse with most provinces limiting highway towing speed to 80-90kmh).
That said, it still doesn't make any sense that our tow rating does not take into account the presence of a brake controller (that is to say, the stated towing capacity does not list braked and unbraked separately in most cars except trucks).
My bad, that was a typo - I mean our tow rating. Most vehicles (except for trucks) don't list the tow rating with a brake controller installed and the only way to get one is to have your vehicle rated and tested individually.