Flight plans don't prevent accidents.
Being on a FPL only means your body could be found faster in case you have gone missing.
A certain B230 crashed in the Indian jungle and wasn't found for 4 months.
Flight plan with civil and military clearances in hand...
Their secondary use is taxation or extortion.
Spain requires a FPL for every flight, even the pattern flights with student and CFI.
Of course you pay for it.
Nigeria extorts 6000 Naira or about $40 per leg.And you pay up front.
That includes uncontrolled airspaces, landing in Bob's backyard, the works.Has nothing to do with airport landings. They're extra.
All controlled by means of a flight plan.
Everytime anything has to be "registered" it is about money. They tell you it's for your own SAFETY. Get it ?