The rates at the studios are high, I agree, the owner of the studio has to make money, and the provider wants basically the same, sometimes more of what an indy provider would make. I do not feel that a studio provider does a better "performance" overall than an indy provider, there are exceptions both ways, but as a general rule, the session "experience" is better overall with an indy as opposed to a studio girl. The studio girl sees way more clients on average per day than the indy provider so she makes more money, even if the donation was smaller, especially if she is a looker and/or has outstanding reviews. In addition, I would add that it is improbable if not impossible for a studio girl to actually have the orgasms she say she has while you are in session, especially if you are #5 or higher to see her that particular day, that also may explain the higher rates as the work they have to put in to give you that IOP is harder to accomplish as opposed to an indy provider that sees 3 or 4 clients, if that many, in a day. Kinda sucks but that is the way it is!
BTW, I have never been to an AMP so I could not tell you the difference there.