...'Why constant change and who benefits.....'
It occurs because its all part of the bureaucratic psyche and 'empire building'
When a 'newbie' comes in to any level...they have to put their stamp on it,/ alter the status quo so as to be seen in command.
With a surplus of drones to build up the little empires within the Big One, we can't just have folk sitting around doing nothing to do because there is a set of regs/rules, previously fixed and acknowleged by those that have to use them..ie the aviation industry..the must be continually amended, revamped modified and fiddled with until the cows come home, because this creates employment on lovely big salaries and keeps 'em all 'occupied' They make the changes. They benefit. CasA grows, GA slows.
The 'jobs and growth' is all in the bureaucracy while GA burns away to nothing ...all due to the control freaks that wish to modify your every move and produce ever more paper and rubbish.
CAsA denies all this of course.. see the Gibson's latest bit of BS spin doctoring.
"safety"... that's just the buzz word that has allowed all the gross and defective growth of a supremely bastard Soviet...a law unto itself.