'Hard working' is a buzz phrase that sounds like exactly what it is - an emotive expression that Cameron would like to feel encompasses the sort of people he wants to vote for him.
Of course, he really wants anyone and everyone to vote for him, but if he can catch people by flattering them with his spin-doctor's latest mealy-mouthed nonsense - since copied by all politicians given the chance to use the phrase - then he will.
I've heard Ed bang on more about 'hard working families' than Dave - and his bunch are the ones who abolished the 10p tax rate for low earners - and rifled the working man's pensions! Ed's not mealy-mouthed at all - nor two-faced - and if you believe that you'll believe anything!!
You have to earn rather a lot more than £80,000 to bring home £80,000.