Have factory tow system on my X and it is fantastic. It is well integrated into the design of the car. The ball and tongue are removable and there is a vanity plate that covers up the hole when not in use. Also maintains aerodynamic features of the car.
It is fully integrated into the electronics of the car with two different plugs available for different trailer set ups. Specialized software comes into play automatically as the car automatically identifies that you are pulling a load and switches to trailer mode. An icon comes on the dash and the cars suspension and brakes become engaged to dampen sway or wind deflections.
Torque from the electric motors make towing easier than any other vehicle I have used to tow. Far superior throttle control than the Hemi powered Grand Cherokee I used to drive.
Heavy loads suck up electrons fast, but other than that it is a fine tow vehicle.
In Europe there are lots of regulations that must be dealt with by the manufacturer to offer a factory hitch. It is a very expensive and time consuming undertaking to add towing capacity. Liability is a huge thing that the manufacturers need to take into consideration.
Aftermarket bolt on hitches are much less expensive, but would rarely pass governmental inspections in many countries.
I believe that Tesla should be lauded for coming out with a factory tow package.
In the States, Tesla wisely disengages autopilot currently. While it would be nice to cruise down the highway, pulling a heavy and long load, I believe that is still best being done under the control of an engaged and aware human pilot.
There are so many variables that come into play when towing. From people hauling more than prudent, driving too fast for conditions, not having experience with an out of control trailer, or the increases in stopping distances as well as vast reductions in emergency handling. Towing in any vehicle is frought with unexpected dangers.
