GNP generally don't include unpaid economic activities. A paid parents income contributes to GNP, but an unpaid parent's time spent caring for children doesn't.
GNP is only a monetary measurement so if you take another job with a profitable
company, you will increase the GNP but your quality of life will suffer. The
point is that GNP does not measure
GNP is the mean wealth rather than median wealth. Let me give an example where
GPN doesn't reflect reality. Lets assume there is a small country with 10
people. 5 of these people make $200,000 and 5 of these people make $20,000. If
this countries GPN is $1,100,000, then the GNP per person is $110,000 which
doesn't measure the correct well being of anyone in the country.