I am surprised that the Economist does not talk about something pretty obvious to me: migrant sex workers are more and more working in the high end et middle range markets. UK is not part of the Schengen Area but still is Europe's biggest magnet for migrant workers. According to many serious sources, migrant sex workers account for more than half the sex workers' population.
High end clients, except maybe for the few rich narcissists, are not stupid. The girls get to some very nice hotels to work for 15-20 days, they have a cultural level comparable to the high end british escorts and they provide often better service.
Simple market law: an increase of the supply for a constant demand.
One would expect that a lowering of prices would help recruit new clients. I am not so sure, however, that it does so. Who among us would claim that the price had anything to do with having a first experience with a sex worker? I guess that, at best, existing clients could increase their number of visits. So, at the end of the line, the equilibrium price drops vertically.
It's an easy article for the Economist: the methodology is exclusively based on the quality of the informants. And I trust them for that. They talk to maybe 10 or 20. They use 4 or 5 of them in the article. The problem is with the very limited scope of the article.