Conrad Zimmerman said:
I can't confirm prostitution, as I haven't run across it (and I wouldn't say the inclusion of it makes a game mature; hate it when used as a catch-all for sexual content, as sexual content can be totally juvenile) but the game does feature some romance options that can develop with companions, and you can be in a polyamorous relationship, so it's really kind of progressive in some ways.
If you haven't come across it in 60 hours, I'd say it's safe to assume that it's not there - good to know.
To me it's part of the setting, it's something that belongs in a dystopian world where your survival hinges on what's available to you. It's not unreasonable to include at all and the absence of it is telling.
I don't see how it can't be mature because we know that there wouldn't be any porn included anyway, which was never the point - none of the previous games had sexual content in them (any that you'd see anyway).
The potential sexual visuals don't interest me, but I do care whether building a settlement and having prostitutes would have an effect, such as heightening morale and making settlers work harder.