An old man mailing his recently deceased wives ballot isn’t on the scale of what happened in Washington, that actually happens all the time Republican and Democrat. Washington was chaos but like a combat zone it was organized chaos.
That actually was what most of the dead people voting was. Nothing appeared to be organised. It was just a lot of incompetency, with a lot of it centered in King County (Seattle), probably because nearly a third of Washington State voters live in King County.
Not that King County's elections system isn't screwed up beyond human comprehension - but election official incompetence doesn't necessarily equate to voter fraud. Our elections are generally fairly clean. There's no reason to believe that there was an unusual amount of fraud relative to any other election.
No one was expecting this to be such a close election, after all - the polling didn't show that.