My mother and i have exclusively used supermarket fuel in all of our cars right back to a 1980 V plate 2 litre Ford Granada L and never had any problems with carburettors and or injectors.
I also worked in a Fuel Filling Station for around 6-7 years and all the fuel came by lorry straight from the refinery either from Avonmouth/Kingsbury or Erdington Birmigham
Fuel has to meet BS EN590 (Revision e.g 2016) for Diesel
BS EN228 ( " ")For Unleaded
Bs En7800 ( " " ) for Super
Fresh fuel then has additives dependent to the retailer added upon loading into a tanker,
The Morrisons i worked at had between 1 and 2 deliverys a day. 1-2 X 38,000 litres
Not sticking up for but stating the facts.