1) road signs, which are predominantly graphic based
2) public information signs. Eg no smoking. Also usually picture based albeit does often contain text instruction as well
3) beach flags indicating where to swim etc.
All of these are enforcing by-laws yet none specifically text driven. In fact when conveying simple rules to people, it often makes more sense to explain that in meaningful images as that enables anyone to understand the message, even if one doesn't understand the written language (eg tourists).
However, the original specification, which in the case of the signs are laws and for software is code, is text, not in visuals. There in lies the difference. I think visual aids like dependency graphs will help us visualize code and communicate ideas like in the signs you mention, but due to the reasons I mentioned previously text will still be the preferred method for specification, or in software engineering, programming. For example, visuals only go so far. The best visual specifications I can think of are blueprints, which I'd argue still require a little of reading to understand. But in certain domains, as I said, text is a better medium.
You can't beat written word. Corps are not lining up to rewrite their bylaws in a bunch of connected drag-and-droppable blocks. I really don't think it's just inertia, the preciseness, versatility,and ease of examination and editing, and permanence of written language is hard to beat. Same with source code.