Just for laughs:
In a 1970s home, heating that would operate without electricity was perfectly normal.
Central heating systems have always relied on electrical pumps, but I'll grant you that more homes had stand-alone gas fires or even (shock!) open fires. Hot water was also more likely to be stored in a gravity-fed cylinder than made on-demand by an (electricity-needing) "combi" boiler.
In the 1970s, not being able to process card transactions wouldn't be a major issue.
In the 1970s I can't remember card transactions being "processed" at the till - the details were recorded on those roll-over carbon machines and processed later, so absolutely no difference at all if there's no power.
In a 1970s office, it might still have been possible for some work to have been done in the absence of grid power, especially if safe emergency lighting was available.
These days, of course, the absence of water for hand washing or toilet flushing is actually an H&S issue and can close offices and schools, many of which have stores of water for such purposes which are supplied to outlets by - you guessed it - electrically-powered "booster" pumps.
In the 1970s, most people's telephones (at home and elsewhere) would still work even if the mains failed. No one was reliant on a mobile phone system that would quickly collapse if there was a wide area power failure.
Not sure how valid this argument is as many cellular sites have some amount of battery and/or generator backup (the bigger sites anyway), as do central exchanges. If you have a wired phone, chances are that it will work through a power cut.
In the 1970s there were no cities with "computer optimised" traffic management,
I refer the honourable gentleman to the 1969 film, The Italian Job where a large plot point revolves around a city-wide computerised traffic management system being compromised.
Ho hum. Have fun!