Some 1964 and 1965 Skylarks had them. My 1964 has one. Google shows lots of images of right hand mirrors on both years.
On the '64 Skylark mirrors you can rotate the bezel and use it on the right. There was a company that made right hand mirrors for '64 that weren't remote control. '65 are one piece, I don't know if they made a right. I converted a left remote mirror to right including the cables and installed on my '64 Skylark. The rear vision isn't the greatest, but I like the twin mirror look.
They didn't make a right-side match to the remote driver's side in '65, only the manual mirror that is not a visual match. The '62-'64 Buick-Pontiac reversible remote mirror is almost a visual match for the '65 driver's remote, but a little bigger. I put one on the passenger side of my Sportwagon. You're right, the actual functionality of it is not great but it looks good.
Mine was likely added (it's a remote), and is more about looks. It is easy to look around with no roof or shingles in the way of vision. I never liked the "van Gogh" look, and am happy it's sticking out on that side.
Hey guys thanks for the great feedback . I think if I can find another left remote I'll try to make it work!