They weren't getting hammered for all the costs of owning your own home. Different world back in the 70s. People with quite good jobs could still rent a house from the council and there were simply a lot more of them back then, in those pre- "Right To Buy" days that precipitated the housing crisis we have now. Over two
million council houses were sold at a discount to their renters; one could cynically view it as gerrymandering on a massive scale in that people who bought their council houses cheaply might be more likely to vote Tory next time.
There were some desperately poor, admittedly; but some were canny and could afford stuff like this - and new cars - because back then, mortgage interest rates were crippling so the relative costs of owning your own home were quite high.
That was more a rental thing back then - if you had a customer liable to default on payment the one thing you could do was fit a slot meter to the set. You could still buy those meters to fit to TV sets back in the mid-80s; there was a good trade in renting out refurbished first generation, even second-generation colour sets back then that had come out from the big rental chains. There were warehouses where you could buy sets by the van-load, at prices varying upon make and condition. I used to make a few quid taking first generation sets donated by friends and family, going over them and fault-finding as needed, cleaning them up and setting them up to as good a standard as possible and selling them as second sets for the bedroom.
A trick of the trade - how truthful I know not, but it wouldn't surprise me if it was true - with defaulting rental customers was to stick a pin through the aerial cable. When the customer rang up to complain that the telly was bust you'd visit and say the set had to go back to the workshop but you didn't have a loan set - but it wouldn't take long any way.
After a while, they'd ring up and complain - and the response of "well, you'll get it back when you pay the rent owed on it" usually produced the goods...