supermarkets have shelves full of them
Yes, especially in downmarket ones, because the tins last forever.
beans on toast, baked potatoes with baked beans
Some people used to give things like that to kids quite often.
They're getting more and more popular in Poland now with plenty in the supermarkets there.
Mind you fish finger sales are huge in PL and have been for years. Must be a retro 70s thing.