I've wanted git blame for laws for years, but I suspect what would end up happening is one scapegoat would be selected for each bill to make all the changes, so it would just be that one person on each bill and it wouldn't really tell us who made a change or why.

You should check out Klaxon: https://github.com/themarshallproject/klaxon That way you can setup all the sites you want to keep an eye on.