Explain the difference in the flight training for a NPPL and a JAA/EASA licence, that matters.
I believe (don't quote me) .....
Less instrument time
Less cross-country navex time
Shorter qualifying cross country.
Probably more, but I don't have the time to look it up at the moment, it's unlikely that the 13 hours is just padding !
Restrictions shouldn't be automatic based on the price you pay. A first class or second class seat. The idea might work for an airline or train journey to grab a few bob but should the same principles be applied to your freedom to hold a pilots licence.
Going by this argument, you would probably say ... "I've learnt to fly, I've got a PPL, I can call myself a pilot .... so let me fly this Boeing and have the same rights and privileges as someone who spent a lot of money on CPL/IR/ME".