I sense a loaded gun?
Young refs can earn more per hour than most multi-national fast food chains will pay them with the addedd bonus of work flexibility. Some sports do not pay umpires at all (Rowing, Hockey? tennis-poorly if at all). Others such as the football codes and cricket pay according to grades like b'ball. At the highest level Cricket Union & and League officials are required and remunerated enough to be full time. High ranking AFL Umpires who do all games in a season would gross 60-70K. I dont know the current game rate for an NBL ref but am certain that it is nowhere near rates for highest level footy and cricket.
Refs at local levels earn their money given that they are expected to manage the area that normally contains players, coaches and crowd and officials of varying knowledge & skill with a fair bit of emotional bias thrown in for good measure. In some ways it can be easier to ref b'all at a higher standard because player & coach game knowledge is better and most participants have a similiar skill level.
Good luck with a basketball crowd though - erratic at best and pretty close to the playing arena. However if a refs expects that spectators will exert pressures and is still able to concentrate on combining with the other officials to get the job done, then the real payoff is an increase in life skills. More valuable than any match payment.