Thats not true either. Do you think a "Science" teacher at Muslim Madrasah Private School or at a Christian based School is going to "exert themselves a lot more" than a Science Teacher at a top performing Public High School?
That's beside the point and while we are on the topic, if someone is slacking in their job because the system is flawed and has a whole lot of associated problems (read '
anything most things Government-related'), it means that someone needs to address the problems and fix them, not that everything else that works better should be reduced to that level of incompetency simply because it exists alongside.
My point is that if you are a business owner and hiring someone for a job in your company, you'd be taking just as much care with the selection as you would with anything else (or at least, ought to). But if you are working for $12/hour in a goverment agency and were put in charge of hiring people for positions you don't care about, then you're going to spend as little effort as possible to get the work done, so you can punch out at 5 pm and still get your paycheck at the end of the week.
Ignoring the context of the employer and making the sweeping generalization is where you went wrong.