It's a legal definition. If you wanted to be philosophical about it the deterministic viewpoint supposes that no individual is capable of giving "consent" as the notion of freewill is an illusion, but that's beside the point.
If someone wanted to make braindance chip and fill a building next door with "consenting" hookers and the kind of "clients" that comes with it, there are very few people that would support it just because some 20 something with nothing better to do decided they wanted to be a doll. They wouldn't want to see it, they wouldn't want to see someone like that setting examples for their daughter. You can call that virtue signaling if you want but when people live in a society the general consensus of that society matters.
I think you may believe that the dolls are human trafficed slaves. The Dolls are a very high end sex worker, somewhere between prostitute and pornstar. There are regular "street hookers" or Joy Toys, in the game walking around, talking to people in cars in alleys and parking lots. Braindances for sexual experiences are some one else recorded acts that you get to plug in a re-live and re-feel. So the dancers at Lizzie's wont sleep with you, but if you like them look up a BD and enjoy. There are actual victims of human trafficking also in the game. Which is absolutely seperate from sex work, its sexual slavery.
A brain dance chip and a doll chip are not the same, again i think you're blending all the "sex" into one thing
Everyone who looks at porn does not all see the same video or fetish, its a spectrum. Two people who both admit to watching porn, will likely not be watching the same thing(s). If person A likes videos about "males" and person B like videos about "females", they both can admit to watching porn but they are watching two different things. So if you only know person B likes females when it comes to porn, and then person A says simply "i like porn" we should not just assume that means they like what person B likes.
Most people drive cars, most people dont drive the exact same car as another person in there immediate area, and is likely that if both people own two exact cars one VIN number apart and everything else matches, they dont drive the way the other driver does.
Yes desperate people may find themselves doing desperate things to make ends meet. And there are lots of modern workers in the sex industry they are exploited or taken advantage of IRL.
A doll turns "off" and then the program delivers a high end experience to the user. Remember V plugs in and then it picks ideal candidates for the experience, then the doll is on a program, and the program drives itself, the doll has to guide V to what V needed from the doll.
A joy toy is an active, alert, sex worker. Like a regular prostitute.
A brain dance actor appears to be dancers or porn stars who dont sleep with everyone, buy everyone has access to the experience of sleeping with them
Sex Slaves, are bought and sold in various story lines all through the Kabuki and Northern Industrial District - mainly connected to the "monster hunt" story line
Also, if free will is an illusion, we should have no laws, because it doesn't matter, because we have no freewill. So what happens will happen regardless a no one can stop it. There is a Tinfoil behind Afterlife you can go talk to Gary the Prophet all about it. So lets not work off that
Also Cyberpunk is not a game about sexual desires, its a dark future, taking a few themes from modern humans and presenting an extreme for you to consider. Gun Control/Violence is one of the themes. Sexual Freedom and Prostitution are very taboo in the US, it is one of the themes. Another piece of this is technological advancement, and mega corporation profits, and how that stratifies society. V lives in the world of the poor that the super rich in safety and luxury live of off. And being that they can control politics, they continue to enable the stratification. Its a cautionary statement on humanity and its present course. The point of that statement is to oppose the idea that the general society doesn't want the prositutes like you indicated
You dont have to be comfortable with the concept, you don't have to think its okay, you don't have to like it. You may see it as rape, like some one may "feel" raped when their pictures go out on the internet without consent. These are legitimate feelings. However I dont think we need to push the idea that this is some game about a society comfortable with rape and its part of the main story line of the game that players must interact with