The problem is having people available to do the work that is needed to keep the system useful and up-to-date, which includes writing code that will parse the ToS, maintaining it, and upgrading programming languages, packages ... and most probably lawyers.

So where those diffs are hosted is a tiny cost of what is needed to make it work.

All these require effort. And effort can be paid with one of two things: time and money. And for someone to have time to work full-time on this, they need to have ... money to sustain themselves.

Thus this kind of project needs money => that either can be a grant, donation from a big entity, or business model. Donations from users are not working for long-term sustainability in most cases of good projects for society. Or at least I don't know a successful project like this.

People are too eager to expect some other person to invest their own time and effort in an open source project without considering the consequences of such an expectation.