They must be getting enough people to buy these expensive photos, otherwise they wouldn't be so popular at these attractions.
I give them credit for identifying a need and taking advantage of it. Often times, I'm not in a position to have a photo of me and my wife snorkeling, or getting off a boat, or in the middle of a ride. However, when you look at the prices, it is unbelievable how much they charge. The majority of the time we decline on price alone.
My problem is customer value. I think the current model is terrible, and needs to be fixed.
Let's say that I'm in the majority, and only 10% of the customers actually purchase the photos. If they charge $20 per photo, and take 1000 photos, then they make $20x100 = $2000 per day. The other 90% walk away muttering about what a rip-off it was, and disappointed that they couldn't get the photo, and the 10% who bought it try to justify in their heads why it was worth the money to spend for one photo.
Many of these places pre-print the photos in hopes that people will feel guilty and buy them. If they don't buy it, then the photos get thrown away. What a waste! All that effort taking the photo, processing them, printing them, and even time spent trying to sell the customer on them is wasted!
Here is a better option, that could improve the experience for everyone.
What if the price was only $5 per photo, which I think is more reasonable. If this increases the chance of buying a photo to a conservative 50%, then let's look at the business model now. If we use the same numbers as before, $5X500 = $2500 per day. Now 500 people leave the attraction with a good experience, and a photo to go with it. I would also argue that it would cost no additional amount of work to process the 500, then it does currently to handle the 100 people in the prior model. The people who buy can also post or share the photo with family and friends, and provide free advertising for the attraction. Everyone leaves feeling good, since they paid a fair price for something they wanted, and more people were able to take advantage, providing customer value to many more people. I would even argue that the % would be much higher than 50%.
Even if the companies who run this service see no immediate improvement in sales with this model (doubtful), the free advertising and increased satisfaction (part of the whole experience for the customers) would provide long term growth for these companies, which would eventually give them the sales growth they are looking for.
