The law was written in the 1970s to apply to some entities in some ways, to other entities in other ways, and not at all to yet other entities. This was intentional on the part of those who wrote it. No theories are required to observe such a basic fact.

Unless maybe your point is that there weren't any lobbyists in the 1970s, that there were but they weren't corrupt like now, or that any political era you didn't hear about from CNN was some golden age? That's cute.