No, it is neither that plain ot that simple. And iI say that as someone wdo has been in a wheelchair at WDW for decades.This has been explained several times already on this thread, and ad nauseum on the many, many, MANY previous threads on this subject. But allow me to attempt to explain one more time.
1. It is Disney policy that any wheelchair or
ecv guests board an empty bus first. It is a safety issue.
2. It takes a lot of space to maneuver an ecv into the secure down slots inside the bus. Wheelchairs, to a lesser extent.
3. It is not safe to attempt to do that on an already partially filled bus unless the guests already in that area are off loaded while the chairs/ecvs are boarded and secured.
4. Off loading all those guests, along with their bags, strollers and children in arms is disruptive and needlessly prolongs the boarding process.
5. A bus can hold in excess of ( for the sake of argument) 50 guests. Let's say the ecv or wheelchair guest and their party are #40. Now you have to get at least 20 people off the bus, load the ecv or chair and their party, and reboard the previous guests before continuing to load the rest of the people waiting in line. Now add a second ecv who is back at #48. And you need to repeat the off load, board, reload all over again.
The current procedure may not be perfect, but is the most efficient method they have been able to devise, so far. If you can come up with a better mousetrap, I'm sure Disney would love to hear about it. Personally, I'd rather know why the Transportation coordinators weren't doing a better job at reducing the wait between buses when demand is that high. The scenario described regarding wait times at a park are not normal.