Dont google and mozilla review source code of addons?
"This version has been screened and approved for the public. Keep in mind that other reviewers may look into this version in the future and determine that it requires changes or should be taken down. In that case, you will be notified again with details and next steps."
Perhaps this also depends on the number of users...
[1] https://labs.detectify.com/2015/11/19/chrome-extensions-aka-...