I don't imagine my friend was the only NNEB nanny working in the US as a nanny not an aupair. The Eappens lived in a very nice house, they weren't penniless they could have lived cheaper and had better childcare. So what was the priority?
Your friend was probably one of maybe ten - twelve - fifty British nannies working in the US at the time?
Even if there were two hundred of them, are you claiming that this British training school turned out enough nannies to staff every MC home in America? Are you claiming that the Eappens could afford such a nanny?
You say they 'weren't penniless', as if the average doctor couple early in their careers should have been able to afford the pick of the nanny crop. I am here to disabuse you of the notion that living in what you would consider a 'very nice house' and being a doctor equals 'wealthy enough to afford a premium nanny' in the US.
The average family income in Newton MA today is $138,000, which puts it squarely in middle class territory. This means parents there will struggle to send kids to university because they will not qualify for much in financial aid. When the time comes, they will draw on university savings plans (which means they sock away money while the children are small) and take out loans, perhaps a second mortgage on a nice house in a MC area, perhaps income from investments. This is solid financial planning for children you assume will live to see the benefits. They did not have their children low in their priority list. Everything they did put the children first. They had a long term plan just as most of my neighbours in a similar suburb of a large American city do. They trusted someone who represented herself to be a capable and enthusiastic childcare employer just as millions of other families do.
Newton has well regarded schools, which means property taxes are high. It is a safe community, with a very low level of crime. This indicates its police force is well staffed, again thanks to property taxes. Newton has a massive and very beautiful public library, again funded by property taxes. There's a public pool and all season rink - $$$. All of that is for the benefit of the children who live there, and it contributes to the price of houses, which in turn contributes to the ability of parents to finance university education, and so on ...
If the Eappens were earning about the average MC salary in mid 90s (which would be the case because she was only working PT and they were both starting out in their careers), and subtracting a substantial amount every month for life insurance, mortgage insurance, mortgage, car payment, property tax escrow account, perhaps an investment account, very likely retirement accounts (IRA, Roth IRA, perhaps 401k through their employers), medical school and possibly undergrad school loans, and trying to put money aside for college savings for their children, they would have been hard pressed to afford a British nanny with a fancy certificate. This is how American MC families live. It's not as swishy as it may look from far away across the ocean.