filing a flight plan certainly does NOT 'take care' of PPR.
True but it does beg the question as to WHY NOT?
I think the most likely answer lies in airport management being one of the last bastions of trade union power and restrictive practices. I have been told, face to face, that the airport ops office will not discuss anything with the Customs people (down the corridor) or with anybody else, and the tower (which gets flight plans addressed to xxxxZTZX, IIRC) is not going to pass them to anybody else "downstairs" either.
Flight plans could easily serve for Customs PNR which - across Europe - is the most common issue with preflight notification. But as I say the airport staff refuse to operate that way.