I believe cashflow requirements make negotiating easier (provided there is room for negotiation). I'm not even going to entertain your offer for $120k. Not because I know my market value is greater than that, but because I cannot meet my financial obligations at that point. Even if I'm a clumsy negotiator, I'll get closer to my max compensation in that situation purely because I have a higher floor.
I think the expectation that you drive a car that is "reasonable for your income" doesn't really hold in the parts of the tech industry where I work; It's pretty normal for highly paid people to drive junkers or not have cars at all, at least in my area and industry; Even sales people don't seem too surprised.
Because life is more enjoyable if your car doesn't make your commute suck more than it absolutely has to?
The best programmer is worth quite a bit more to the company than an average programmer. The best salesperson is the same way.
The best major league pitcher or quarterback is worth quite a bit more to their franchise than the average or the best minor league/second string replacement.
Why should someone producing more value for their company be paid the same as someone producing less?
You can't focus on just the prestigious adjective and decide that it's unfair when the person involved has considered it and appears to believe that it's fair.