Quite a bit of snobbery on this thread. My pet hate is huge supermarkets with far too much choice. I am also shocked at the huge differences in price from one shop to the other. Simple things like lentils, cheese, tinned tomatoes, shampoo etc. can be selling in other supermarkets for double the price I pay in Lidl for similar or better quality.
I cannot understand why the OP refuses to try the stores recommended. If you try the produce and honestly are not satisfied then you can tell your MIL that you tried but didn’t like the produce. I feel she is so happy with her choice that she wants to share her recommendation. She probably finds your refusal to try (with an open mind) inexplicable. As do I.
People eating and drinking on the go
Should women have equal pay and opportunities?