The whole thing becomes difficult if you need someone with you when travelling. I can't speak for other airports along the way. But I know that in Wellington (New Zealand), the Qantas ground staff responsibility appears to be from the check in counter to the gate for people in wheel chairs. I assume they would also take you from one gate to another in transit - full stop.
This does not SEEM to include - getting food,getting to the ticket counter, going to the toilet, really anything else - would be from the goodness of the ground staff's heart (and they are seriously quite busy). I would be reluctant to send my father off like this without arranging a companion at each airport that he will be at for any significant time - unless he can see well enough to get around.
What I have observed in Wellington is that they take the person in the wheelchair to just before security and leave them on their own there until the staff come thru on their way to the gate (this can be a long time if you get there two hours before the flight). When the staff come thru to go to the gate, they then bring the wheel chair bound person with them thru security and customs to the gate.