Federal taxes aren't the only taxes. State and other taxes are factored in.
Rent may average at $1100 in an ideal world, but near cities, $1100 is increasingly rare. Every time this is mentioned someone will chime in and say "yeah but I live in rural Nebraska and pay less than that." Which is fine. But then your employment options are slim, most jobs aren't paying $40k a month, not everyone is a tech contractor making 200k a year from their bedroom on a lakefront, not everyone wants to be or can be a tech contractor, and a lot of jobs performed by "normal" people (people on HN are generally highly paid and anything but typical) will involve long commute times unless they're living in the middle of town... in which case rent prices shoot up fast.
The average person also needs to pay for health care in the US (even if their company provides insurance, they're fucked when they get sick because insurance covers very little for most people not in very expensive programs). They have car loans. They have college loans. They need to pay deposits just to move. 9-5s are being replaced with 9-6s and people have less free time.
When you factor in all of that, the "average office worker" looks like a dream life to a lot of people. What people considered a boring hell of a life in 1965 is a fantasy unobtainable to an increasing number of "average" people. Comments claiming it's "easy" for "average" people here make me think some people live in a bubble detached from all reality.