Well, back in your mother’s time, there were prostitutes, and there have always been prostitutes. Sad thing is that, while women of easy virtue were rare then, the chaste woman is among the minority these days.
The Euros are actually quite civil about the whole thing and there is a certain etiquette about the whole thing and the relationship is mutually beneficial to all parties involved.
It's pretty obvious what the man gets out the deal and he is supposed to be very discrete so as not to embarrass his wife, the young lady gets security, stability, an eduction and access to upper levels of society and other opportunities that never would have been available to her, and the wife maintains her position and that of the children as the mans wife without having to worry that he will leave her for a younger woman, as is very common in the US.
Overall, a remarkably workable way to do things that works for everyone involved.
In contrast, the whole Sugar Daddy thing is pretty crass and unappealing.
It's a pure business transaction with little or no pretense at a relationship like the European model. There is even the potential of signing a contract of sorts which would be an interesting document to review to learn what is spelled out.
Not exactly my cup of tea, but at least it precludes a palimony suit. Think of it as a pre nuptial agreement that dispenses with the inconvenience of actually having to get married.
For the gold digger demographic, it's very economical and efficient because she can just pocket the cash that otherwise would have been wasted on an expensive wedding.