They could probably just pay pornstar wages and get pornstars who would consider it easy work.

@1 My guess is pornstars are more expensive.

@2

My guess, too. But they don't need to get the superstars and they could avoid having people who are uncomfortable about the work, which would probably result in a stronger product.

The series is being shot under union contracts; SAG-AFTRA has jurisdiction over background performers and has very strict rules regarding nudity and simulated sex acts. As The Guardian article notes, the consent form given to performers did not mention specific contract language pertaining to nudity, and that they had the right to refuse to participate at any point if they became uncomfortable. This is why union contracts exist: to protect workers from precisely the sort of exploitation tbis situation represents.