Toilets in handicap bathroom and staterooms.
It would seem that designers don’t ask the ADA community what is necessary to transfer to a toilet. For example, our stateroom toilet has no space on the side where the wall is and the toilet is not ADA height. We have to use a toilet seat riser that leaves me perched up high. Then, the handicap bar on the left is too high. Transferring and cleaning requires acrobatic contortions.
The toilets on deck are taller but they have fold up hand rails that, while useful for a lot of people, stick out from the wall eight inches preventing us in power chairs from backing up to the wall and transferring easily.

So, a necessary function becomes an adventure. But I am learning to be a contortionist.