As you were saying this, the thought occurred to me that if we are trying to figure out whether budget implementation bills include items that ought not to be in them, the best way of doing this might be to look at the history of budget implementation bills in Canada and see how they have developed. Perhaps there was a golden age when all they did was something much narrower.
As we know, the fundamental role of the government is to secure supply for the ongoing operations of Her Majesty's business. The fundamental role of the House of Commons is to decide whether or not supply ought to be granted. The budget, effectively, is a way of saying, “This year, we are changing our priorities and the supply we're going to need is going to be different.”
I'm assuming that some stripped-down version of that was what happened in the early days. If we looked at where we've been, we might figure out whether there was some point at which we crossed beyond what's permissible, and see if we could roll back to that point. We actually have many precedents.