Anyone who feels the minnie vans are a good deal, then yay for you. My point wasn't that no one would use them, it was that I don't think enough people will use them to keep it in business.
$20 may not sound like a whole lot for a single trip, but then you have to remember there is the trip back as well. So assuming you only go one place all day, your at $40 a day.
That's car rental prices at that point. I got an 8 seater Toyota Sienna from Enterprise for $420 for 10 days when we were there in June. On the downside, we had to park and then still take trams or walk to the gate, on the upside, we could go to disney springs, or universal, or the grocery store, or anywhere else we wanted without having to drop another $10-$20 each way. Taking into account the fact that we traveled more than one place each day, we did better than break even.
When the entire group didn't want to go to the same place, there was Uber. For 2-3 of us to jet from the resort to a certain park was always less than $10.
You have the following types of people:
A: Is a patient saint and thinks the buses are just fine
B: Isn't totally happy with the buses, but balks at $20 per direction to take a van.
C: Is fine with paying around $40 a day for transportation, but decides to just rent a car at that point.
D: Is willing to pay for extra transportation, but already does so, and is therefor already an Uber user.
E: Is willing to pay $20 each way to use a Minnie Van (whether that's because name brand trust or car seats or whatever) and is not inclined to use Uber, a rental car, the free buses, or any of the other available forms of transportation.
Do people in category E exist? Sure they do. Are there enough of them to support the entire fleet of Minnie Vans? I honestly don't think so. This is Disney setting out to solve a problem that private contractors have already solved.
The inherent benefit that Uber will always have over something like the Minnie Vans is that Uber drivers can just bugger off and do something else when no one is requesting rides. Or they can flood into WDW and queue up all around Disney Springs, Resorts, and various parks when ride requests are surging. Disney doesn't have this benefit. They are paying people to drive a fleet of vans that they have to maintain on property (versus individual drivers maintaining their own vehicles) and they have to pay a set number of employees to run those routes. This will lead to a lot of times were driver's are just sitting there with nothing to do and other times when the next Minnie Van won't be available for 15-20 minutes.
At the end of the day, there are several other ways Disney could improve transportation at WDW without trying to reinvent a wheel that is already established and doing fine. Take that investment and put it into the monorail that is very literally falling apart. Or the Bus system which failed us so many times the first time we went that we didn't touch once on our entire 10 day trip this time. Or the fact that they have created a huge bottleneck at MK by forcing everyone to load up on Buses, Monorails, and Ferry's.
True Story, leaving Mk one evening the lines were so long that we ran an experiment. We split the group into 3 pairs. I walked to the Contemporary and called an Uber to take me to the transportation center. I arrived 25 minutes before the group who took the monorail and 35 minutes before the group who took the ferry. It shouldn't take over an hour just to get to your car after a 12 hour day at the parks. Minnie Vans don't solve that.