I have found that Ubuntu doesn't always follow their posted rules. It seems apps that were developed before the Software Center and placed in /usr/share, etc. were kind of "grandfathered in." But to get it in the Software center I put everything in /opt, as they say they require, to not give them a reason to reject it.
I would guess most users only have one "user" on their system, but some do have multiple.
The 777 permissions on the /modules folder would work great, but some see this as a security risk. I really don't know why.
Developer, Bible Analyzer
But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness. (Rom 4:5 AV)