DFC
Do you actually fly aeroplanes?
Here in the UK, most airfields have a means of filing flight plans but most don't have public internet access. There is a way to do most things by phoning around but for a long flight one needs to get a narrow route briefing and that can be done only over the internet.
One cannot "prove" that something was not possible. The court could always say that in 2005 a pilot should carry a laptop with GPRS/G3. I am 100% sure that departing from the middle of nowhere would be no defence at all if you busted a notamed airshow.
The present system is OK for pilots that do "burger runs". Perhaps this is what most GA VFR pilots do?