That's not true, it has to do with tongue weights, tow speed restrictions, and trailer brakes.
In Europe, almost all trailers have brakes, whereas many small ones in the US do not. In Europe, towing is often restricted to speeds as low as 45mph by law in some countries, whereas say in Texas the limit is 80mph. Related to the speed issue, in many European countries tongue weights are allowed to be as low as 5%, whereas in the US its 10% or double.
If you tow a trailer with very light tongue weight and its own brakes and you restrict yourself to low speeds, almost any vehicle can tow it without issue.
The US by contrast is the only country I know of to have created actual safety guidelines for towing that actually perform a variety of stringent tests, such as a steep grade test, a rapid lane change test, a high speed test, and more created by the Society of Automotive Engineers (J2807). While this isn't mandated by government, the fact that this standard exists has impact in the courts, and so manufacturers heed it voluntarily.
Its not bogus though, and frankly many of the tow recommendations are outright dangerous if used like many Americans would towing unbraked trailers at speeds of 55mph or higher as is often the case since unlike in Europe Americans often tow trailers vast distances where traveling at 45mph is a road hazard. The reason is that while its much more taxing on the vehicle, more tongue weight to the tune of 10-15% is inherently more stable. But it puts more load on the towing vehicle's frame, its tires, and if not braked its brakes, and so the tow ratings are usually MUCH lower or if already low in Europe than not recommended at all in the US. Its not a conspiracy or BS to be dismissed though, but sound engineering science.
tl;dr: If you're going to ignore the SAEs tow guidelines made for the US, then be sure you tow like a European and get a self-braked trailer and restrict your towing to 45mph backroads or feeders, and don't try to tow like an American.