The problem is that if they shut everything then it will concentrate more people in supermarkets which increases contact and reduces the chance of supermarkets getting stocked up properly. At least lots of small shops with social distancing and cleaning measures means the economy doesn't shut down completely and it still reduces the chance of the spread. Just because all of those businesses will be allowed to be open it doesn't mean that they will. Most sensible people will probably avoid all those and a lot of them will voluntarily close anyway.