newbee – I’d like to see an explanation of finances before claiming that they “make it”. Depending on where you live and how many children you have, 80K (pre-tax) may not even cover tuition.
If you want a simple explanation, they are either 1: have 0-1 children (maybe 2), or 2: not paying tuition (either by getting a break or discount for being a school employee, in which case the “non” tuition is really post-tax income).