I'll try.
When you look at any compensation regime for any large employer, there's an acknowledgement that you want to have a portion of that salary based on performance--not guaranteed absolutely, but based on performance. My colleague is just confirming that because of the Auditor General's status as an agent of Parliament, there is no such performance pay for her because of that independence. The same thing happens, for example, for heads of quasi-judicial tribunals. There is no performance pay for heads of quasi-judicial tribunals, because it could be seen as an attempt by the government to influence their decision-making.