Texan77, your oversimplification of PPP calculation, presumably not devised by yourself, is simplified to the point of making it entirely inaccurate.
GDP calculations do not take account of efficiency, but simply of money prices. You might want to look up the Economist Big Mac index as this gives a very simplified and easily understood way to get one's head around what PPP is and how it works.
Here's The Economist's page on the subject: https://www.economist.com/big-mac-index
They apply the index to assess relative currency values to give an insight into whether one currency is under or overvalued in relation to another. They also make clear that the Index is based upon PPP calculations.
However, in your example of the Chinese maid. Your suggestion that her labour would not be used in the USA because it is inefficient is not correct. In the Chinese context, it might well be an efficient use of time and therefore money, just as it is to have a housekeeper, cleaner, gardener, chauffeur or cook in the United States. The only difference is that due to other factors within the economy, this form of labour is more costly than in China making it less affordable to the USAian population.
To give a somewhat relevant example.
Many years ago, as I was finishing my time at university, I was offered a job with a global consulting firm. My wages, even starting out, would have been high enough to make most USAians envious. On the other hand, I was expected to work very long hours.
Within the consulting industry, such hours are normal (even if not entirely healthy). People in the field tend to hire in services to ensure that they are able to maximise their downtime. They hire cleaners, gardeners and the like. The goal is to regain time by paying money. The net result is that the apparently high wages are not quite so high when the return exchange of money for time is taken into account.
A colleague of mine worked in a firm where many junior consultants did not even have homes. They stayed in hotels all the time because in that way they outsourced ALL the services of living that 'normal people' take care of for themselves. As they worked away from home five days a week, on the client's money, they saved a lot of money in comparison to normal folks who had to buy or rent a home that was costing money even when not in use.
Was this kind of lifestyle 'inefficient'? Absolutely not. However, it was a lifestyle that I decided not to pursue.
If one can afford to hire a maid to do time-consuming work within the house then why not do so?
Most people in China cannot afford to do so, just as in the United States, but, just as in the USA, those who can do so, often choose to do so. After all, if I am working 60 or 70 hours per week I do not want to waste my valuable free time on cleaning, laundry and other household chores.
The hypothetical Chinese maid earns enough to live decently and, for example, where a Big Mac might cost $5 in the USA it costs about $1.25 in China. The maid is not well-off by any means, but she has enough to manage life and afford an occasional Big Mac. In China, a Big Mac is still something of a luxury for many and, from my time there, one can eat better for less in other places!
Sticking with the Chinese maid, she earns a hypothetical $200 which using the Big Mac Index is around $800 per month. That may not sound like much, but that excludes her living accommodation, very often food and at least some of her clothing needs. So, not a bad deal for her.
A final thought, had I taken up the consulting position, had I been seconded to China, given the relatively low cost of living there, I would have lived like a prince! Again, something I saw while I was there was that the relatively well-off lived a remarkably lavish lifestyle given that the basic costs were so low. Even where I live now, although the situation has changed and prices have risen a lot, the effect is still noticeable. I could afford domestic help here quite easily.