... that they probably don’t keep your password saved on disk (hashed or otherwise) or make use of a login token. My Roku is powered by my TV’s USB port and shuts down every time I turn off the TV, so that is why I lose my login.

Netflix must keep my some sort of login token because I never have to re-sign in.

Edit:
I solved this problem by making the password as simple as possible. You can also download the Roku app on your phone and connect to the Roku wirelessly and use your phone keyboard to enter in passwords