The consent isn't about the software, it's about the name/handle.
Whatever the legal specifics might be, I think you'll find that an awful lot of people think it is obnoxious to collect money (or so) on behalf of someone else without having them agree to it first.
You say I'm pretty sure you can't collect money on other people's behalf though.
What is it you think tip4commit is doing that is being objected to if not collecting money for someone else? Bitcoin are close enough to money for the purposes of what I was saying.
