At least where I am from, you are allowed to tow heavy trailers (>750 kg) with a B drivers license, if both the car and the trailer combined weigh less than 3.5 t. Light trailers (<750 kg) can be towed by any vehicle up to 3.5 t with a B license. If the combined rated weight is above 3.5 t you need a BE license as well and you have to drive slower.
At least where I am from, you are allowed to tow heavy trailers (>750 kg) with a B drivers license, if both the car and the trailer combined weigh less than 3.5 t. Light trailers (<750 kg) can be towed by any vehicle up to 3.5 t with a B license. If the combined rated weight is above 3.5 t you need a BE license as well and you have to drive slower.