I believe it's all tied to NMMA standards and there is a formula that uses the gross weight of the minus ballast and is then divided by a standard weight per person to come up with the capacity number.

It's a bit of a sticky situation and I think manufacturers have struggled with what to do. In the past, I think they put in smaller ballast systems to pump up the capacity. Now, with the focus on wave/wake, I believe some are using the max factory number. The SA, for example, has people capacity calculated for the liquid lead ballast system even though that is an option and some folks may never equip their boats with that much ballast.

I've heard of some areas where this is being monitored. Mostly where residents have complained about the wake boats and perceived damage they cause.