It would be nice if they open sourced the software. It is a cool concept, but I bet overhead was too much.
It doesn't work like that. They rather keep everything within their control, or sell it to an interested party, than simply publishing everything online where people can make use of what ChangeTip has invested plenty of time and money in. Other than that, there are already certain other tipping bots that do their work equally as good. Or you can get your own developed. The only question is.... Will you invest your precious time and money into something that might never reach a point of being profitable for you? I definitely wouldn't.
It can definitely work like that and it has happened many times before on other projects.
Likewise, if you read what they have said ChangeTip even discussed doing so per their public postings but didn't believe volunteers would accept the liability. Also, again as they have publicly stated, they have not been able to find a buyer for it, everyone is at AirBnB now, and they have been running it for the last few months at a loss.