You never see an economy car towing a trailer, and do you know why? Those cars, along with compacts and other lightweight models, are not heavy enough to tow a trailer, especially a full one. Why does the weight of your vehicle matter so much when you want to tow something? It has to do with how the engine and brakes are manufactured to ensure they can work well under intense pressure, and with how long the vehicle is. Those three factors make it possible for your vehicle to tow a trailer without causing the towing vehicle to break down.
Heavier Cars Tend to Have Longer Wheelbases
While the strength of the bumper and hitch attachment are certainly factors in how well your car can tow something, they mean nothing if the wheelbase isn't adequate. The wheelbase is the distance between the rear and front axles of your car. In lighter cars, which tend to be smaller, the wheelbase is rather short. If you were to try towing something that had any real weight to it, that weight could drag down the rear half of the car. And if you have a short wheelbase, the front end of your car could end up pointing up into the air. The longer wheelbase (and thus heavier vehicle) provides sort of a counterbalance to that trailer, keeping your front wheels on the ground.
More Weight Requires a More Powerful Engine
The heavier your vehicle, the more weight your vehicle's engine has to be able to handle on a regular basis without strain. If you have a lightweight vehicle, your engine is made to handle that weight with some interior passengers and cargo. It's not made to pull an extra load along with the vehicle and everything in the car. If you tried, the strain could cause the engine to wear out sooner at best and cause the engine to stop working at worst.
With heavier, bigger cars, the engine is configured assuming you'll be carrying more weight in addition to the vehicle. More passengers, more cargo, and so on. It's easy for manufacturers to make that engine capable of towing a trailer as well.
Heavier Cars Have Brakes Made for Stopping Heavy Weights
When you replace the brakes on your car, you don't get just any brakes. You get brakes made for your specific make and model. And those brakes can handle stopping your car and what's in it, although the more you put in your car, the more careful you have to be about stopping. With heavier cars and utes, the brakes are capable of safely stopping much more weight, including trailers (although you still need to be cautious and brake sooner).
The size and weight of the trailer and its cargo also come into play, of course; even if you have a large, heavy SUV, you have to get a trailer that does not exceed the vehicle's towing capacity, and you have to keep the cargo within a certain weight limit.
If you need to buy or rent a car trailer, double-check your vehicle's towing capacity and then speak with trailer companies about the available options. You'll be able to choose from several different styles of trailers and find a perfect fit.