It might just be the place I work, but I noticed the handicap accessible toilets are a good 6 inches higher off the ground.
In:
For many people with physical limitations, it’s easier to get back up again to standing afterwards from a higher seat. Less strain on the back, the knees etc.
For someone transferring from a wheelchair to a toilet or the other way, the slightly higher seat helps with that too.
It’s not a huge change, but an extra couple of inches simplifies things a lot.
As I understand it, they are closer to wheelchair height making the transition from wheelchair to toilet (and vice versa) easier.
Someone else might have a better explanation.