Erm, been happening a while now - wife applied for a head teaching job advertised @ £85k. No different than other sectors - if you want to attract good candidates, you need to offer a good salary. it's particulary difficult for schools with bad reps - they have difficulty atracting good staff so they offer more money.
And what to you mean "how dare they offer five figure salaries"? Headteacher have difficult specialised jobs, long hours and lots of stress - they have to be good class teahcers, excellent at admin, have a lot of financial responsibility, have to attend a lot of training and have massive responsibility - they deserve the money imo.
Or are you simply jealous?