Well, what an interesting debate!
If I may, I would like to tell you a bit about a fictional character. He is a professional businessman that utilizes the services of escorts on a regular basis. When asked by fellow “hobbyists”, he always says that he is a “collector of sexual experiences”.
He gets tested for STDs every 4 weeks. He has never had an STD, although his lifestyle would lead one to believe that he is more at risk than others. Truth be told, the first thing he asks a “provider” is for a copy of her latest “call card” before continuing with the appointment. (a “call-card” is given to a person who is anonymously tested for STDs. It has the control number of the test. When you call in, you use the control number to maintain anonymity.) He has, at times, asked the provider to allow him to call on her test. Do to his unusually high amount of spending; many providers are now being tested on a regular basis, if for no other reason than to keep his business and the business of a few friends that have adopted his stance. Needless to say, he NEVER has had un-protected sex (although he is aware that only abstinence is 100% safe).
He is very anti-drug. He has refused to see a provider that he feels is acting in a way that would indicate drug-influence. He has made it very clear that he will “black-ball” any provider that he gets convincing evidence of drug abuse. (He has a very large group of friends that respect his opinion) He has assisted a few ladies into rehab when they had problems and asked for help. When he has assisted (by providing an income and the fees for rehab), he insists that they stop “providing” until they are clean. Every time he has made the offer, the lady has accepted and completed drug rehab. Only once has a lady relapsed.
He spends an inordinate amount of money in his pursuit of the ultimate sexual fantasy. Some people spend money on ski trips, boating, etc. He spends it on this. His choice. The $$ amount that he spends is miniscule to what other friends of his spend. While he will not disclose his total spending, he has said that 4 friends of his recently had a discussion about total spending. The 4 of them spent in excess of $300k last year on their pursuits.

I have a strong feeling that the majority of those not involved in the industry have NO IDEA how much money is being talked about. The total industry outlay (pardon the pun) would probably rival many of the larger “traditional” service industries.
The fictional character has become friends (or as close as one can become a friend) with a few providers in this industry. A few, he has assisted with their tax returns (hard to figure out how to depreciate breast enhancement surgery LOL). Of the providers he assisted last year, the average income DECLARED was $85,000. That is AFTER expenses…. net taxable profit. These providers are NOT the top earners in the area. In fact, they would probably qualify for the 35th percentile. Keep in mind, this is what they DECLARED.
This character has seen providers that are models, college students, housewives, actresses, salespeople, and many other mainstream professionals. About 50% of the providers are full time escorts. BTW, of the college students that he has seen, to a one, all say that they would not be able to attend the college of their choice if it were not for earning a good living, with the flexible hours, they find in this trade.
His outlook on the morality? He strongly believes that it is better to pursue his exploits in the manner he does, rather than get emotionally involved with multiple mistresses all over the country. Not only would the cost be greater (more on that in a bit), but it would also be very unfair to all parties involved to develop deep emotional ties.
He thinks it is a moral requirement to “give back” to the community of ladies that give him so much. This is why he actively promotes safe practices within the community. This includes the things described above, but also includes methods of physical security.
(As a side note, a very good provider was recently beaten and robbed by a psychotic client. The same prosecutor that had tried her (unsuccessfully) for prostitution; refused to prosecute the perpetrator of the crime. The reason? He said that the client reasonably explained it away by saying that he had made it very clear that he was looking for rough play. The prosecutor said that she was “asking for trouble” when she accepted the appointment.)
Now, before you condemn the fictional character, understand also that he has a healthy sexual life outside of the escort arrangement. He is painfully aware of the possibility of sexual addiction, so he purposely takes frequent “sabbaticals” to assure there are no signs of an insatiable desire that would be indicative of addiction. He also consults a psychologist regularly, not only to keep a handle on his sex life, but also for overall good mental health maintenance.
Enough of the fictional character. I hope you are understanding of my use of this method of explanation.

Now, on to a few additional thoughts.
How is it illegal for a lady to accept $500 for an hour of “tryst”; and not illegal for a mistress to accept $20,000 a month for an apartment in Manhattan and miscellaneous spending?
How is it illegal for a lady to have consensual sex with a gentleman for $600; when it is not illegal for a lady to accept an evening on the town, requisite with dinner, theatre, ice cream stop, limousine, etc in return for an evening of pleasure?

It does not make sense.
Last but not least, how many times have gentlemen attended a singles bar… purchased drinks and food all night long for the group of 6 ladies… in hopes of having an evening nightcap?

In my twisted mind, it should be illegal to lead a guy on and let him spend his money… only to NOT have the “final result” come to fruition!!
I know these are off-the-wall comparisons, but what truly is the difference?
These are just a few thoughts to ponder. I will end this horrendously long post by complementing everyone for a wonderful debate. It is refreshing to see a topic with such opportunity for harsh words, being discussed with such respect. Kudos to you!!