As you didn’t specify only shops, I hope you are aware from these forums the ludicrous and lengthy detour these one-way systems impose at some major stations?
At Finsbury Park, if changing from National Rail to the tube, towards central London, you have to actually EXIT the station on the eastern side, walk past random strangers in traffic-clogged streets, re-enter the tube station on the western side, a good ten-minute diversion for a fit person, assuming green signals at pedestrian crossings. When the spiral staircases were open, you could get from NR platforms to tube level in under a minute!!
Even coming from tube to National Rail involves exiting the station and re-entering, at least doubling the transfer time.
Kings Cross is similarly stupid, and they persist with ‘following the arrows’ late at night, when there are so few passengers you could drive a bus through the spaces between people if the rules were relaxed, in accordance with passenger numbers !!!
I don't think all one-way systems are good, but they can often provide benefits. For instance if it was possible to separate the flows to and from platforms 8-11 at Euston properly (which it isn't really) this would be so much easier to use. And yes, it's good where supermarkets are designed for one-way systems (with the middle and end aisles to allow you to backtrack) because it makes things less congested and more pleasant to use. Whether they need to be in place at all times is more debatable, but with regard to Kings Cross didn't that have a one way system in place even before COVID, i.e. platform ends for exit only?