Do you think Nav Charges are per passenger?
Effectively that's the way it works... The slight increase in Movements but Huge increase in Pax generally means the aircraft are getting bigger (I'm sure the loadings are very unlikely to have significantly changed); the bigger the bird the bigger the Nav charges; combine that with the changes to rates charged in the past 10 years...
Not saying Ireland does it better, but you don't see their ANSP generating 100s of millions in profits, even though it's in a much better position to do so as the majority of it's customers are not locals (companies or citizens) and the governments bottom line is in a far worse position.
I'm not so concerned about the back office roles as such; because forgetting the empire building element, most of those can actually 'support the front end'; my concern would be the massive amounts of money spent on 'development' of the latest machine that goes ping, with no economic case for said machine.
Various projects have absorbed huge investments that will never pay back. Lots of them for nothing more than ideology; or some other reason...
Having worked with a more 'modern' version of TAAATS in Ireland, with 2 people on every console, there is a huge difference between safe and safe enough. When was the last time Ireland closed airspace due to the lack of staff, or instigated a 'short break' procedure, or had excessive over-time all the while having two people per sector. Would be interesting to see the 'breakdown stats' comparing the two ANSPs.
IFATCA has a 4 eye policy for safety, Australia has a 2 eye policy (some times 1 eye or no eye policy) for economic reasons. There are significant limitations going forward for fixing this mess, but a redesign is definitely a must; unfortunately it has to come from the front end back, not the other way around; like every other 'restructure' for the past 20 years. No 'supervised handovers' when one controller is staying on position, much smaller risk.