If we did have $30,000 more on average, as the article states, how would it be used? The case is obvious for the poor, but as you go to higher income brackets more and more of the possibilities fall into "luxury" and "status symbol".
Take, for example, the rise in the cost of college education. It's absolutely bizarre that in an era of low fiction information, tuition has actually gone up. That is, until you consider the credentialing as a form of signalling for limited jobs at the high end. The colleges aren't getting funded to expand the core mission of education, they're chasing each other to provide a premium experience that will attract people with a pedigree, who subsequently raise the status of that institution.
From that angle, automation's effect is to shuffle around the job landscape, not to directly increase productivity. More minds on higher value jobs - but eventually we start cutting into the highest value stuff we can think of. What automation doesn't do for us is expand our ability to be creative about what work is and what jobs could be done that aren't. That capability is directed through our social structures and "what people will pay for." Anyone good at conversation knows that you can have the same room and the same people and achieve wildly varying outcomes in discussion. You can have an economy that "shrinks" because less is measurably produced, yet people feel wealthier on average. Indeed, that's central to discussion of open source software and its commodifying effect.
In conclusion, no, we don't know. Social science is a fragile thing and the things that seemed obvious to one generation have a habit of being discarded by the next. Maybe the $9000 of income inequality is, in fact, the important number, even if we can fabricate another bigger number with linear extrapolation.
Material needs, probably yes. But not all needs are material needs.
> as you go to higher income brackets more and more of the possibilities fall into "luxury" and "status symbol".
Those are loaded words; one person's "luxury" is another person's preferred entertainment.
> It's absolutely bizarre that in an era of low fiction information, tuition has actually gone up. That is, until you consider the credentialing as a form of signalling for limited jobs at the high end.
That's probably a contributing factor, but it can't be the primary reason tuition has gone up so much, precisely because, as you say, there are only a limited number of jobs for which this signalling is useful.
The primary reason tuition has gone up so much is the fact that student loans and grants are so widely available. Colleges have simply raised their prices in order to consume all that extra money. Most of those loans and grants don't go to people who view a degree as a status symbol or a signalling device; they go to people who, rightly or wrongly, sincerely believe that a degree will give them a chance at a better life, and the wide availability of financial aid means that more people are likely to come to that conclusion. (IMO, we've pushed that lever too far; many of the people now using loans and grants to get degrees will not get enough of a better life to make it worth it to them. But that's a whole other discussion.)