Today a Paypal billionaire is launching his car to Mars because he thinks it's cute. Meanwhile:

[CaptainTruth]

5. No way, not on the maiden test flight of an unproven craft.

It was the Falcon Heavy's first flight, a test flight. The odds of something going wrong on the first flight are much higher. No one risks losing a $100+ million satellite on a first test flight, that's why dummy payloads are used. The test payload could have been a simple block of metal, SpaceX chose a used car.

This has nothing to do with taxing anyone. It has everything to do with testing a new, unproven, rocket design.