DN.
You havent quite grasped the point of social tariffs.
They have never been about subsidised fuel and they do not result in subsidised fuel ever, they were introduced to stop huge additional costs being put on prepayment meter use,
All they do is drop the price of the power to the same as that companies 'best' deal available to none prepayment customers and add the direct debit discount before the charges for having a meter are added on.
It still means prepayment meter customers pay more than billed customers but stops it being more than double the cost (as that's what most of the energy customers did when the meters became more usual because they added the charges and also started with the fuel being much more expensive.
So no person on a social tarrif will ever recive fuel cheaper than someone who does not qualify for the tarrif it just starts off at the same price. No energy supplier who does not or did not start off with the fuel unit price for prepayment meters on a massive hike compared to billed customers was ever obliged to provide a social tarrif other than the direct debit discount aspect of it. And they have been being phased out for quite a while now.
I expect you also fall into the section of people who think water is free if your on benefits that's also make believe but water companies do have to have a social tarrif but its got very little to do with out of work benefits to qualify you need a household member who has certain (actually named) disability or illness that requires higher water use and your water bill for the year gets set at the average for your area you do have to be on a meter but you won't get charged more than the area average for it.
Your acquaintance with the 5 kids she only needed 2/3 when she had her first child she wouldn't have had to activly seek work until the dc was 16 about 3 possibly 4 years ago it changed to 11 so for 15 years she only needed 1 straight away she would have needed an under 11 so that's 2 but she would have been perfectly safe for the next 5 years minimum.
As when they first changed it from 11 it dropped to 7 quite quickly after the 11 change and then again quite quickly it dropped again to 5.
She started in the early 90's so she would have needed to time another one for last year.
So perhaps she had them for other reasons like ohhh she wanted them.