I think people are forgetting the promo person is on site all day long. We are usually one of the first to arrive and last to leave. I'm lucky that the events I go to, I'm usually a chief official too (so there all day anyways). No dealer is going to send someone to sit at a tournament all day and pay them (unless that dealer is a skier). As others have said as a promo boat owner, it is not just the cost of hours. I'm pretty lucky that most tournaments I pull are less than an hour from my home. I think the $25 is a nice start, but is not close to the actual cost of time, depreciation, insurance (you can't have a bare bones policy) and maintenance.
Also the hours limits on boats have come in the last few year. As boats are returned to the dealer, they limit both tournament and personal hours. And it is not just one brand, I have seen this from both Nautique and MC.