I dispute those numbers.
There has been a very real growth in nominal median household income, while people claim that real household income is flat even as far back as pre-1970.
Meanwhile, we see in the long term reductions in the percent of that income spent on food and clothing, as well as a 31% increase in spending on shelter while the median size of shelter increases by 56% and the household size (persons) decreased by 15%. That means spending 84% as much on shelter (and 71% per area per person, but that's irrelevant except to say that we're not cramming lots of people into cramped little spaces).
Even since 2005, the food expenditure was 13% and it's now under 12% (personally, it's 3.9% for me, and I eat out a lot--frequently spending $15 for one meal, but not nearly on every meal). Across the past decades, people have been enabled to put more money into savings, buy more and better healthcare, and spend much of their money on entertainment and other discretionary spending.
That doesn't even get into what accounts for "equivalent goods and services" these days.
Dual-core desktops hit the market in 2005. That's quite a shock compared to 66MHz 486DX or 200MHz Pentium Pro chips that cost $200. Never mind the constantly-falling price of RAM, hard disk, and SSD. PCs, costing thousands of dollars in the early 90s, were $350 commodity items in the mid-2000s.
Cell phones of 1983 cost $4,000 for the phone and $55/month for the service, plus 42 cents per minute voice. Two hours per week would net you $250/month service. That's a $9,000 phone and $550/month service today. Somewhere along the line, we got consumer cell phones with $100/month service; then we had $250 flip phones, $40/month service, and text and video messaging; and now we have heterogeneous hex-core smartphones with 2GB RAM for $350, backed by $60/month service with high-speed data (although I pay $35/month to Ting instead).
An ISDN 128K line in 1998 cost $35/month and required a $250 modem. Today I get 200Mbps Comcast service over an $80 modem--it's $54,687 worth of ISDN lines all tied together for $83. Do you remember DSL talking about their wicked-fast "three megs" in 2005? I have 70 of those.
Even cars only standardized transistor radio and air conditioning in the 1950s. Now we have antilock brakes, traction control, EFI, complex suspension systems, air bags, vehicle dynamics that prevent rolling and skidding, sensors and cameras to assist in lane control and parking, and all other manner of highly-complex systems with many moving parts. Somehow, we don't pay a bigger chunk of our income for these things: cars cost about the same proportion of our income, but come loaded. This will remain true when we all have self-driving vehicles.
Your argument is essentially that somebody else has told you that we're producing more, we're not earning more, and our buying power is not increasing. My argument is that the percentage of the median income being spent on goods like food, clothing, and shelter square-footage has gone down; people have spent more on luxury, leisure, savings, and medical care; and that the common goods and services we consume have rolled in more stuff we couldn't have afforded years and decades ago, essentially taking the same portion of our money and giving us more stuff in exchange.
Reality suggests buying power has increased. A lot. People like me--at $75,000 income--are pocketing all the extra money. I bought a house and paid off the mortgage in 3 years. I'm getting ready to buy a car, but I have a couple debts I want to clear out first (adding payments on top of other payments is stupid). I bought myself a $7,000 piano for the house. I put $18,000 into my 401(k) and $3,385 into my HSA this year (which puts me at $57,000 when you exclude my 401(k), compared to the $52,000 median income of the US). I'm 31.
I'm living like a friggin' king here, dude, and I've been diverting a lot of my money to debt elimination and to my 401(k). My 401(k) is largely there to act as a loan source, rather than a retirement fund. What I've accomplished in five years is ludicrous. I'm going to buy a $25,000 car, add cameras and Nest smoke detectors to my house, and put in hardwood floor and new insulation--and pay it all off in the next 2-3 years, while dumping the maximum into my 401(k). I take home around $50,000 after taxes, counting my HSA as money I get to keep because I can spend it on healthcare. You're whining because you spend all your money and wish you had more--a state you'll be in forever, even when you're buying twice as much crap and complaining that you're still not the slightest bit richer while surrounding yourself with hot tubs and hookers.