"a very good indication how you value the effort of child-raising and her career that she will give up for you (it's still usually the wife that follows her husband)"

Is that still the trend these days? Are most couples able to afford to only have a single working parent anymore?

What you usually see is that one spouse (the wife, usually) spends time with the children when they are very young and then works part-time. Obviously, that impacts career progression. Salary data would support the theory. It's not a single working parent, it's 1.5 working parents for a few years.

I suspect you are right. Now that I think of it, I actually recall hearing a podcast on this (Planet Money? Freakonomics?) where they dissected the statement around women only earning something like $.75/dollar compared to men. I believe they found that if you looked at earnings before having a child, they were equal, and that the reduced earnings came from taking time off or sacrificing workload (and presumably total contribution) for flexibility. This then resulted in not advancing as rapidly as say, someone putting in twice the hours, or who did not take several years off and thus has that many more years career experience, despite being the same age.

Cases where wife follows her husband in job-related relocation are more common than the opposite, and they are typically detrimental to the partner's career.

Spot on.