alright, thank you all for your helpful replies.
Now I will threadjack my own post.
So the parks that offer paid express passes Like the extra income, agreed?
Like any other product the company wants to sell as many of these as they can.
The Company can market to increase sales. This is mostly benign to the consumer.
Now if you ran the company and wanted to maximize sales of these passes, what "knobs and dials" can you turn to increase sales? Line size.
Maybe the doubters are right and the corporate managers are altruistic and wouldn't tweak line size with an eye towards sales and revenue. The incentive is there though.
Incentive may be there, but there is a fine line they must walk before they screw the entire thing up. It's more a matter of balancing the "perk" with the standby lines, then a matter of intentionally increasing line size. [generally]....... At least, for the Disney and universal parks. I don't know enough about amusement/thrill type parks to give them the same benefit of the doubt.
Basically, you are looking at a basic calculation. The Ride can handle X number of guests per hour. Now you just need to decide the balance of where those guests come from... the Express line or the Regular line. You also need to factor in the perceived value of each line. If you don't balance correctly, Your Express line could be almost as slow as your Regular line..... Or to increase the speed of the Express, You end up slowing the Regular line to a virtual standstill that pisses people off more since they feel they aren't really moving at all.
Universal with their Express does a good job at this. The limit the total number of the one-time use express passes they sell.....And use the variable pricing on the passes to help manage the supply on days that might result in higher demand. (win-win.... they make more money, and also help limit the demand by forcing people to make a value judgement). The unlimted express for staying onsite is set up as well so that it doesn't break the system due to the relatively small capacity of the onsite hotels compared to the guests-per-hour capacity of the attractions in the parks. This is also why the new "Value" won't include the unlimited express.... it increases the onsite capacity too much for the system to remain viable.
In General, This is the same type of calculations Disney makes with their Fastpass system, even though it's free. They limited the supply of their free fastpasses by only allowing you to get one every couple of hours, As well as limiting the number of passes available per window. It created a "virtual line" more than doing a straight Express/Regular setup like universal. Disney has to make the same calculations though on Ride Capacity and the ratio for each method of entry. With the enforcement of the return window now, they are able to better manage that ratio by avoiding the end-of-day stacking of the Fastpass line.
I remember it's also been reported a few times by people that the impression they got was that more fastpasses seemed to be going out and the standby lines were moving slower.... possibly in prep for the next gen version of Fastpass disney is working on. In Theory, since they are able to better predict the actual number of people in the fastpass line at every given moment, they can increase the number of fastpasses handed out in every window since they spikes won't happen like they used to from out-of-window fastpass usage.