The more polished the surface is, the slower it rusts. Polishing bike frames is difficult, if you don't want to lose the crisp edge definition that is a hallmark of an artisanal frame. Even if you wouldn't mind rounded edges, polishing a previously-sandblasted frame is a huge amount of work. Getting down into all the crevices is near-impossible, so some blasted areas will probably remain, and a blasted finish is like a candy-store for rust. I'm imagining the rust looking at the blasted surface and saying "yum!"
Cars, shotguns and golf clubs are easier shapes to polish, plus they were never sandblasted. The classic "gun blue" finish on guns starts with a high polish. The bluing is actually an oxide coating if I remember right. It slows but doesn't prevent rust by itself, you rub it with oil, and some penetrates into the oxide coat and stays there even when the item doesn't feel oily. You couldn't clear-coat over that without degreasing first to get all the oil out.
Higher alloy content in the steel also helps. Reynolds 853 for example is practically stainless, tho Reynolds doesn't call it that, they have actual SS tubesets they'd like to sell you...