With the case of hitch mounted bike/storage racks the "vertical weight" figure is simply an attempt to simplify for mass consumption that there is a huge difference between the cantilevered force applied by a floating bike rack, and the direct tongue weight applied by a trailer for example.
Imagine that 160 lbs centred 1.5-2.0 feet from the hitch on a vertical bike rack lets say. Vs 160 lbs centred 3.0-4.0 feet from the hitch on a platform bike rack. The later will be exerting twice the torque on the hitch. We all realize this but unfortunately Tesla doesn't provide the torque limits. But we can make intelligent decisions with this in mind. For example I am selling the bike 3&4 extension on my Yakima HoldUp Evo platform rack. Keeping it as a two bike rack, and adding a 4 MTB Yakima HangOver vertical rack that will keep the weight much closer to the hitch, and reduce the load on the car.