The all have the same issue: you tied up with what ever meal you are given (regardless if you've chosen them or not). Those are perishable goods. It means that you cannot just drop one meal without incurring waste. Their recipe are not very varied either, which can lead to some less than desirable meal (some are even borderline terrible).

I have tried pretty much all the major offering in the UK in the last 3 years. There need to be something more flexible than that. The big store could easily already make meal kits from their stock for specific recipes that would compete with Hello Fresh and the like.