Working in an industry where Manuals and Policy/Procedure documents dictate, I would also love this.

Eg. in the heavily regulated airline industry, Framemaker still persists as standard. Changes are typically made against a PDF as comments (handwritten or PDF annotations), attached to a paper "Manual Change Request" form and signed by manual owner and passed to a Tech Writer to replicate the change in Framemaker. Turnarounds in order of months are incurred, and where the regulator is involved, I have seen years.

A Git-style version control workflow would work well: - allowing collaboration - change documentation and approval is built in (even better if regulator can use it) - publishing smaller amendments while larger ones develop - reuse modules across manuals (eg. org charts)

However, uptake will occur when the learning curve is reduced...such as a well designed web UI

Pull requests seem especially apt.

If they aren't interested in using some sort of existing wiki or collaboration software or saas, what would make them interested in something like this?

I know nothing about the legal profession, but my reaction would be because wiki software sucks. I'm a designer and a developer and I can barely figure out how to edit a Wikipedia page.

Another question (which I don't know the answer to) is how many developers had never used version control until they were introduced to Github?

I bet there are some seriously big interaction improvements you can make to the average enterprise "collaboration" software.

It wouldn't take that much work to change markup languages, or fix the UI of something like mediawiki or dokuwiki to something that's more amenable to those industries, if they don't like the defaults. Mediawiki might be pretty locked into a database for page storage, but dokuwiki has a git backend plugin, and some other wiki software even supports git backends natively.

Hopefully developers that had never used version control until Github had never written software outside of the classroom.

May your hopes never be shattered, my sheltered friend.