I think there are a couple of factors you're overlooking.
Consider the case of a dental hygienist married to a nurse. In SF, they both earn about 110k a year. So $220k is a high salary, comparable to a physician in a modestly paying speciality.
Here's the thing... I think payroll deductions apply to the entire 110K of each dh and nurse's salary, but only the first $110k of the physicians salary. However, the second salary in the two-income family will be taxed at a high rate, on top of the first salary. Furthermore, physician's husband, who doesn't work, is available for full time child care. The nurse and dental hygienist have to arrange full time day care for their two young kids, which runs about $20-25,000k a year per kid in SF. And because they are a very high income family, over the "ultra-rich" 200k threshold, they don't get a tax break.
Even close to 100k, that second salary may have a marginal value close to zero once kids enter the picture.
That doesn't mean you shouldn't work just because the marginal value is low in the moment - eventually you get to come back up for air, and people who continued to work are often much better positioned to advance again. So there are benefits.
In progressive tax situations that is called the 'marriage penalty' (second salary is all taxed at the higher marginal rate) which is mitigated somewhat by changing the tax thresholds for married people filing jointly. You can file separately of course, and it seems a number of people are living together and filing as individuals, it gets complicated as you get kids because they become dependents (and a tax credit) on one of the people's return.
There is a reason all this stuff keeps a legion of tax attorneys and CPAs employed.
Consider the case of a dental hygienist married to a nurse. In SF, they both earn about 110k a year. So $220k is a high salary, comparable to a physician in a modestly paying speciality.
Here's the thing... I think payroll deductions apply to the entire 110K of each dh and nurse's salary, but only the first $110k of the physicians salary. However, the second salary in the two-income family will be taxed at a high rate, on top of the first salary. Furthermore, physician's husband, who doesn't work, is available for full time child care. The nurse and dental hygienist have to arrange full time day care for their two young kids, which runs about $20-25,000k a year per kid in SF. And because they are a very high income family, over the "ultra-rich" 200k threshold, they don't get a tax break.
Even close to 100k, that second salary may have a marginal value close to zero once kids enter the picture.
That doesn't mean you shouldn't work just because the marginal value is low in the moment - eventually you get to come back up for air, and people who continued to work are often much better positioned to advance again. So there are benefits.