They did over the summer certainly. There were press releases like this:
We know that families can find the summer holidays tough, and our customers are telling us that this year more than ever, they’re concerned about holiday hunger. With that in mind, we are so pleased to be able to offer children’s meals for just £1, with no minimum adult spend, to ensure that those who would normally rely on a school meal aren’t left without.” - that one was an ASDA spokesperson
Then their Good Living posted this when they announced the £1 deal:
Asda has announced its strongest ever initiative to help feed children throughout summer and the rest of the year, meaning kids across the UK can eat for just £1 at any time of day in Asda Cafés, seven days a week, with no minimum adult spend required.
Tesco's announcement over the summer:
Kids Eat Free is just one of the ways we’re helping our customers to spend less at Tesco. We know that costs can add up over the school holidays, so offering free meals to children with any item purchased at our cafés for an adult, is one of the ways we are supporting parents during this time.”
It's nice to run promotions. People can, and should, use whatever promotion suits their family, but the idea that large companies are doing things out the goodness of their hearts when they could do much more to make food affordable to everyone is laughable.