-- That the idea that if they could be SAHMs, every woman would pick that route is utterly misguided. Some women would choose that, others would choose careers, some would do both.
-- That every family will make the choice of who is employed outside the home on their own. My ex-wife didn't work outside the home for many years (by her choice not mine). I know many couples with only a single breadwinner. So yes - the two-income trap is a real thing, but it isn't like it was suddenly law that every able-bodied adult had to enter the workforce.
No. Back when there was class power sufficient for working families to withdraw one partner from the labor market, they did so. Then that power eroded, and they were forced to send the second partner into the workforce. This also involved a wave of inflation that was never reversed for housing, healthcare, education, or energy prices.
> Who is doing the forcing here?
It's called the two income trap[1]. Back when it was traditional that one person worked, the market recognized this reality and prices of everything made it possible to live off of one income. Then, slowly we started seeing more and more two-income families. Two-income families could bear to spend more on everything, so the market responded by adjusting costs higher. Soon, it became difficult, then impossible for a family to survive on one income, so then everyone had to go two-income. Now, the same standard of living we once could achieve on one income, requires two incomes. We've doubled the workforce but gained nothing in terms of standard of living.
1: https://en.wikipedia.org/wiki/The_Two-Income_Trap