About "thee" and "thou" .....?

I have seen several movies in which 18th- or 19th-century Quakers use "thee" as a grammatical subject, where I was certain they would have said "thou." Did anyone really ever talk like that? I would have supposed the screenwriters simply didn't know what they were doing, except that one place it occurs is in "Moby " --the one with Gregory Peck-- in the scenes where Ishmael and Queequeg are being hired onto the ship. It doesn't sound right, but the screenplay there was co-written by John Huston and Ray Bradbury. You wouldn't expect them to get that wrong; but I'm sure "thee" was never used as a subject in The King James Bible, for example. Can anyone shed any light on this?