That is the equivalent of what you are asking. Musk has other forms of income and wealth accumulation that other people don't have. Therefore his salary shouldn't be used to compare to people who don't have those other methods of income. Similarly Tesla has other advantages that help increase demand (or limit the upside of further increasing demand). Other companies that don't have those same advantages can still benefit from increasing demand through advertising.
The only conclusion we can draw from Tesla's lack of advertising is that the company leadership feels that it is not the best use of company money. Any attempt to extrapolate that out to the auto industry or advertising in general is making a lot of assumptions.