It's a widely known fact…
It's a widely known fact in the EV space that the higher SOC (state of charge) you begin at, the slower the charging typically occurs. If you would have pulled up to the supercharger at 20% SOC, then the resulting total miles gained would be MUCH more. That's why Tesla's navigation attempts to get you at the next supercharger at the lowest possible SOC so you get more charge for your time...
So, the test that TorqueNews performed isn't an optimal representation of how fast superchargers can be.