This thread is worthless without pics. I said it once and I will say it again -- I have never witnessed children, elderly or handicapped go without a seat on a Disney bus ever. Everyone who wanted a seat had a seat, those who were able and preferred to stand -- stood.
There were many families just like ours with children and strollers who made the decision not to board a crowded bus expecting others to give up their seat(s), on vacation of all things.
It is my responsibility as a parent to ensure that my children have a seat. I will never feel comfortable with someone having to give up their seat for me on vacation when another bus is soon to arrive. I am not talking about the "real world" bus. This is in reference to the microcosm that is Disney.
The nicest and most friendliest people I have ever met at Disney have been right on these same buses. Every bus I have been on has been a pleasure.
If for whatever reason a neglectful parent opted to board a crowded standing only bus on vacation when another is on its way -- we would give up our seats in a heartbeat. But I have yet to see this.
Every Disney bus that I have rode on, the people were kind and considerate and will wait for another bus. If they are selfish and willfully board a crowded or near crowded bus expecting my seat -- they can have it -- but trust me it says more about them than me.
Most families care about the well being of the children and will not intentionally place them in a compromising situation where they are solely "dependent" upon a strangers generosity.
IMHO, most people without children are independent and don't wish to place themselves at another strangers mercy, when they have the option to wait for another bus. This option is much more empowering.
Honestly, most people at Disney do this -- at least on my buses.