What if they look like this?
Or use one of the many toys that provide erotic stimulation while looking at goats on the interwebs.
Why shouldn't I be allowed to secure services of a willing female? Why shouldn't a person be able to offer sexual services if they so choose? Why are you against people being able to make free choices as to what to do with their bodies.
And if sex work is banned, why not ban porn too? After all, making a porn video is a type of sex work too.
As to sex toys, they are fine and well, but that would be like saying (re your example below) that you should be allowed to rent a U-Haul truck but not any people to help you move. It makes no sense. It's government meddling into where it doesn't belong.
But we are talking about contractual sex, which is different. Just like the government has no say if I help move my friend, but if he pays me to move him we have a contract and it is in the powers of the government to regulate such contracts.
We are not talking about regulation, but prohibition. Should the government make it illegal for anybody to offer payment for help moving and throw you in jail if you do offer somebody money? Should police officers pose as people with pickup-trucks to entrap you into offering them money? Should only people with friends or family willing to help them move for free be able to have help moving?
Now you know the difference between contractual sex and consensual sex.
They are different concepts but with a large intersection in the Venn diagram. I.e. sex can definitely be both.
Because it is regulated commerce.
That would justify a certain level of regulation and not outright prohibition. However, one must beware harmful regulation that are designed to harass - strip clubs etc. are often subjected to that kind of regulation in the states.
Why? It is highly authoritarian, illiberal and maternalistic. It is causing no good, and probably a lot of harm.
See what happened when Rhode Island accidentally legalized sex work.
When Rhode Island accidentally legalized prostitution, rape decreased sharply
What about drugs? The seller is penalized more than the buyer.
So should we penalize just the buyer and let the dealer go? A sex worker is really a seller of sexual services, so is more like a dealer than the buyer in the drug trade analogy.