Again, the Terms & Conditions don’t state 20-30% anywhere. You’re likely looking at the wrong document.
Canonical is a privately held company with numerous revenue streams, as you’d expect. Like most well run private companies we don’t generally have a policy to enable random people on the internet to dictate internal revenue allocation. 
I know of no other privately (or indeed publicly) held companies which do that. While it’s possible that Canonical may ring-fence revenue generated from one product towards financing that department’s activities, I don’t believe that’s something we’d get into publicly.
Sure, it’s simply a matter of programming (QA, testing, legal review etc).