I have been asked the question before "Do you require the ground up or down?" I prefer them with the ground down cuz every home I've lived in has them this way, but if they are installed the other way, I thinks, they all should be the same.
As far as code, the NEC handbook illustrations show most of the receptacles with the ground down but the Exhibit 406.3 of receptacles and plugs shows the ground on the upper side on a 125-volt, 15-amp receptacle.
So, can the dryer plug be upside down or sideways?
As far as that WH install with cord and plug, that looks like a violation not having the correct disconnect unless that meets the WH manufacture requirements. Doubt it!
There are some small squat size WH's that have a built-in cord and plug. (Rheem makes one).