Regarding supervision of children, the entire Disneyland Resort has a policy that all children under the age of 7 must be supervised by someone 14 or older. There are 4-year-olds who meet the 35" height requirement at Gadget's Go Coaster, for instance. That means that they are physically large enough to be safe in the ride's restraints, but that says nothing about whether they are behaviorally ready to be on their own. That 4-year-old would be turned away if he or she attempted to ride without someone 14 or older, even though the height requirement was met.
People visiting the park alone dont suddenly "need" a shorter line, and the whole point of a Rider Switch is to allow the person who didn't ride to get a chance to ride with one other person, which they can't do as a single rider.There is a need for an actual single rider line, for people visiting the park alone, people who are doing child swap, etc.
An attraction that has Single Rider typically has a seating configuration that tends to result in single empty seats with some frequency. Let's say there's no Single Rider offered, but there 100 people an hour who (for whatever reason) wouldn't mind being put in one of those empty seats, as opposed to the 1400 people an hour who expect to be sitting with their party. If the Standby wait is one hour, that's 1500 people in line, with the 100 would-be single riders scattered randomly throughout. The grouper or groupers will have a hard time finding them in a timely fashion, which results in a reduction in the attraction's capacity, which means fewer people get to enjoy the attraction each day, and the line moves more slowly. Everyone loses. Single Rider passes or queues allow Disney to put (nearly) all of the 100 people in one spot where the grouper or groupers can use them to fill empty seats as needed. That's why Single Rider exists. That's also why Single Rider doesn't lengthen the Standby wait. If anything, it shortens it by removing would-be Standby guests from that queue.But, to have the line just to shorten the regular line, in my opinion, is no different than Fast Pass, so why not just combine the two? At least with Fast Pass, they limit the number of people who can use it a day, so it does not take away from the regular line (such as at Radiator Springs Racers).
This is true. Single Rider depends on the fact that the majority of people prefer to sit with their friends and family. If that weren't the case, the wait times would be roughly equal and there'd be less of a reason for Single Rider to exist. But the vast majority of people do expect to sit with their friends and family.If every party starts splitting up and using the single rider line, and other parties use Fast Pass, eventually there will be no need for a standby line because the single rider line will be just as long as the standby line used to be.
Here's the bottom line. Groups in front of you in the Single Rider line make your wait longer. So it's natural to feel some frustration, because of course you want a short wait. But as long as people dont make a fuss about being split up, they are violating neither the letter nor the spirit of Disneyland Resort policies.