If the episodes are in the public domain, that doesn't prevent the original studio from releasing them in higher quality official versions. CBS/Paramount did that with the early seasons of The Andy Griffith Show and Warner Bros. did that with the old 1940s Superman cartoons.
Speaking of better prints of public domain things, have there been any higher quality releases of the 1954 Sherlock Holmes TV show with Ronald Howard? I have a 2008 Mill Creek release that crams 13 episodes onto each disc but it's clearly remastered from very poor film prints. The sound is really worbly in places.
I’ve got that “Sherlock Holmes” set plus a couple of “Best of” DVD’s by other companies with episodes of the show. All the DVD’s are using the same masters, the only difference being that some of the “Best of” DVD’s only have 3 or 4 episodes so they are not as compressed.