So I know this. I had an RP partner who lived in Vegas (or claimed so, and knew a bunch about Vegas so...), and they had some high class places that operated in the open. It's only legal in certain counties, she said, and it's very strict: like you can't go out on weekend and have to get tested to stay safe. (Again, this is what I heard. I did research and I remember it being right, but I did research again today.)
A quick google search and it looks like this is true: it's legal in certain places.
So, yes, illegal in certain places in Nevada. I suspect a writer who didn't do deep research would just claim legal in Las Vegas, which isn't actually strictly true because it's far more complicated than this.
A quick google search and it looks like this is true: it's legal in certain places.
They talk about legal brothels in this article: https://www.reviewjournal.com/local/local-las-vegas/downtown/prostitution-in-nevada-has-its-advantages-experts-say/
So, yes, illegal in certain places in Nevada. I suspect a writer who didn't do deep research would just claim legal in Las Vegas, which isn't actually strictly true because it's far more complicated than this.