...Meaning that around one in two eligible voters in the US simply don't care about democracy.

That's a pretty large leap in logic there janne. Any of the "scientists" in here agree with this hypothesis/conclusion? Can you find any holes/gaps in this?

I believe a more reasonable hypothesis is that about 1/2 Americans are either too busy producing/paying tax/raising their family to make it to the polls

Ah, yes the 47% who actually have a job, or two or three, and produce. This opposed to the rentiers, who sponge and like Mr. Trump pay no taxes.

But once economic liberalization took off in the 1980s, the struggle was won decisively by capital, and labor’s share of total income has shrunk everywhere.

Gary's flippin' out about a tax-stamp

Never said anything about a tax-stamp.

Here's another piece that says your claim of earning figures are questionable and that you need to consider age ranges when talking about income.

By including all age ranges in your estimate...

Hex it on the cards?

Could it be that, for some reason, like people wanting their old manufacturing jobs back, that some parts of the US are not evolving fast enough.
conservative - definition - averse to change or innovation and holding traditional values.

"You can lead a horse to water............."

Goodbye:)