Thanks for this second book review. It's interesting since it can be a good start to discuss key ideas. Thganks for give a summary. I guess I would be bored rapidly.
I agree with your conclusion : we come back lonely and loneliness is sometimes harsh when we receive messages from our sweethearts asking for money and showing less interest every day in our life and hard work.
You also questionned whether it's possible to visit so many countries. I guess it's possible to do it in several years but he mustn't have explored each country very deeply.
John's main idea consists in defending that Western politicians and media who see prostitution as an ugly human trafficking are wrong and that prostitutes in the country he visited had been free to choose the job. IMHO, this is questionable. I think that prostitution is neither free nor ugly but it's sometimes a pleasant trade in which both parts find an advantage in the business eg the case tthat you mentionned "prostitution between elderly western men and young P4Ps from poorer countries is consensual enough even if rooted on regretable economic inequality."
I have mongered in several countries in my life over a few decades (I started when I was 17 yo) and found that p4p is not so simple. I often saw girls pretending to be free but fairly often pimps are not far from the prostitutes. I remember a Romanian girl I had helped to get a new passport after her passport had been "taken and lost by a young man". She had maintained for weeks the indefensible version that she had no pimp and once she got her new passport, she told me a lot about the bad time they had given her.
I also noticed many times that it's difficult for prostitutes to remain friendly with good feelings for their clients. Even when they have no pimp, they are unable to establish a long term relationship. You pay, you fuck and you go. Asian girls (gurls) are just more interesting since they prefer to make their client be a sponsor rather than a one shoot customer. Of course, evryone can find all kind of situations in every country.
Not that I pretend that pimps are everywhere, there can be inexplicable reasons for a gurl to resort to prostitution. For example, their need for money doesn't always come from poverty, but I read about all kinds of different reasons why they need money. I thinks it's important for us to avoid those who don't have a strong motivation to do it, not that I defend a moral attitude, but I think that gurls who have freely chosen prostitution are often the best ones.