One of the reasons for that is Mathilde's nearly unbroken habit of being the biggest Wizard in whatever endeavour she is involved in.
Only Wizard in Stirland.
Only (surviving) Wizard on the Sylvania campaign.
Magister amongst journeymen on the K8Ps campaign.
Loremaster for the ducklings.
Lord Magister on the Dum expedition.
Project lead on the Waystone Project.
There has never been a time when Mathilde was under the authority of another wizard, or in competition with a wizard while under anyone's authority.
The population of wizards is also pretty small, at least for journeyman and up. About 150 of your own wind? Anyone who does that inside their own wind will quickly get a reputation. That won't stop it, but it makes things much, much harder. The Greys are bound to take that stuff very seriously, so it would happen even less there.
To a lesser degree, that still applies between colleges, because that's still not a huge group. But for Mathilde specifically, the fact that she's a Grey matters. That's the last group you'd want to fuck with.
But in all, I don't think outright falsehood doesn't happen much in wizard circles. Squabbling about degrees probably does, but it would still happen less to and with the Greys.
But yes, the fact that there's never been another wizard with authority around matters. They
might have tried with Hexensohn of she wasn't so notably busy at the time, and also if it wasn't an embarrassment they wouldn't like more eyes on.
Really, Mathilde is the one who comes the closest to having done it on screen, but even in that case it was deliberately being better than someone.