Because the Swift video is not a 90 degree alley dock.
The "alley" portion of the name being the critical part. It is suppose to simulate backing into an alley from a road, not docking in a commercial warehouse facility.
They made the test easier over the years by not requiring blind side alley docks but the course is intended to simulate a public road. Thus the standard they set for the alley dock was a 90° backing test.
Some states only due the parallel parking test and there have been some suggestions to change the tests to have forward and reverse tracking skills tests.
But the reason you don't do it as suggested above in the Swift video is it doesn't test the skill that the people who voted at AAMVA chose to test.
Here is the text
That "position your vehicle parallel to the outer boundary" ensures it is a 90° alley dock test. The choice of that test was probably arbitrary.
Last edited: Oct 1, 2020
Reason for edit: Add info.