This is coming more and more of a thing I've noticed with older shows on Netflix that never saw a true HD edition. I don't really know how they do it, but I assume there most be some filtering program that masks compression and interlacing and does some kind of slight internal resolution increase. I suspect this can be done extremely cheaply if there's an original digital source, as it can be done in automated batches. But, like I said, I don't know much about that stuff.
Not so much Netflix good as DVD bad I suspect. Typically they used to cram several episodes onto a DVD making the most of shelf space, and the bit rate was low enough for MPEG2's worst habits to be most visible.
Meanwhile Netflix uses much more modern compression, so even their SD episodes, of things in the UK like Buffy and Doctor Who, look better than their DVD equivalents. The technology is just ten long years younger.
However, for reasons, a little while back when Voyager was on Amazon Prime, it looked crappy, so I'm guessing either the masters are in a very rough state or Amazon prime was still tweaking its technology.