Disclosure: I don't work in the tech sector. I agree with you that I doubt that the budgets of tech company's transit benefits probably wouldn't make a significant impact in the effectiveness of public transit (or even get the same amount of bang for the buck).
A problem with many of the initial transit offset arguments was that they didn't take into account that given the presence of the buses how many people chose to live in communities farther way from their work, when absent the buses, they would have moved closer. This and other externalities.
Regarding "the media is obsessed with viewing private buses as a symbol of privilege" is because it is a symbol of privilege -- Unless you want to make the argument that it's a symbol of disadvantage. Someone who has a personal driver is more privileged than someone taking a private bus than someone taking a private car than someone taking a public bus than some poor chap who has to bike or walk everywhere.
The reason why the media and much of the non-tech public has disdain for the buses is that it creates two cities. One set of people has access to travel means A and B and the second set just has access to B. The last time that sort of forced social sorting was prevalent in the United States was in the 1960's when there were White and Colored water fountains. These are the connotations the general public thinks about consciously or subconsciously.