I have been involved with companies with government security clearances and organizations simply worried about intellectual property theft. As a rule, the most serious of those organizations do not allow subcontractors free rein of the building, which janitors need.
(Edit: Yes, I am aware of some high profile failures.)
I think you can get subcontractors that specifically provide cleared janitors. (The same way that for example the NSA famously uses cleared contractors for things like IT.)
But anyway, Docusign surely isn't an example of such a company or agency.
This has not been my experience. I was FSO for my organization. I was responsible for periodic training and internal audits. I have no way to know how well any other FSO or any other organization ran their periodic training and internal audits.
(Edit: Yes, I am aware of some high profile failures.)