Here in Spain I know a family that hired a young girl "au pair" (in their case a Polish girl who wanted to learn Spanish). The father told me they paid her about 400 euros/month + food and accommodation, so it's not something prohibitively expensive.
To use your numbers, a person would have to make less than $11,000 a year for that salary to be half their income. I doubt there are many people reading this discussion in that income bracket.
There are many things in life that aren't feasible if you are at the poverty line: Apple laptops, electric vehicles, extended vacations, etc. I would argue that the only difference here is that many people are deeply uncomfortable with the idea of paying someone to take care of their children in the home.
I am living abroad, and I will let countrymen/women correct me, but in Portugal you can hardly aspire to earn more than 1500 euros before taxes, in the best companies.
Most of them pay less than that.
So a university degree will land you around 1000 euros, a bit more if you are doing lots of overtime.
Renting a flat will always be above 300 euros, or 500 in the biggest cities.
So unless one if living with a significant other, and reserve one salary for such expenses, they aren't possible at all.
In Spain the salary level on average is around 25% more than on Portugal, but given the actual situation the real numbers on the bank account aren't that much different.
And I am writing about people with degrees, let alone those that only learned their profession hands on the job.
