The underlying data is all binary, but LabVIEW has built-in diff tools that allow you to compare diagrams (the source code) between two vi's (LabVIEW files). As a result, you can use it with source control and coordinate multiple developers much like any other language. It isn't really necessary for the underlying data to be text. Search is also pretty decent.
The beauty of dataflow languages is that it frees the developer to think about what is really important while the runtime handles the nasty concurrency issues. Does this approach work for all problem domains? No, but it works fine for a lot of stuff. Nothing comes close to LabVIEW for making concurrency trivial.
Its a pity that LabVIEW and programming languages like it haven't seen much mainstream adoption. In the right hands and in the right problem domain, a good LabVIEW dev can do things that would make other programmers' jaws drop.