You know, as a kid, I honestly don't remember seeing Scramble or Super Cobra in arcades back then. But then, if I did see them, they probably wouldn't have made much of an impression on me since there were so many space shooters out there back then.
I think it's weird that sometimes Konami says that Scramble is part of the Gradius series. Especially since the only things they have in common are that they're side scrolling shooters and you can bomb targets. But then, sometimes Konami puts Rush N Attack/Green Beret in the Contra series, so yeah.