The oft-used phrase "all are agreed" doesn't make grammatical sense to me.
It means "all agree" or "all agreed", or even "all are agreeing", with "all" being the subject.
"All are agreed" instead appears to make "all" the object, with some unspoken subject, as might be the case with "all are accredited" or "all are married". So what would be the subject here?
Or is the phrase just an idiosyncratic idiom? And if so, I wonder how it came about?
(Of course, it could mean "all are engaged in being greedy" I suppose :-) )