Unfortunately, I don't think the problem (with Congress) is technological. If GitLaw were implemented, a lobbyist wouldn't be making a pull request directly, they'd influence someone to do it for them so it wouldn't be traceable -- which is pretty much the way it works now.
Because now there are hundreds of people to check. We don't known exactly who did what.
With GitLow there will be one direct person responsible.
SCM helps a lot with source code. Imagine 400 people software project without SCM.