if passenger business picks up any more, it may not be possible to restore a full pre-pandemic level of service, without removing some of the (new) extra freight business.
they've still got shortages when I've been in any of the local Tescos, but this is all pretty anecdotal: presumably other shops are either fully stocked or their customers don't mind going without stuff.
IMHO most supermarkets carry too many lines. Aldi & Lidl are perhaps the other extreme, somewhere in the middle would be nice.
I have had no problems with our weekly shop from ASDA. Everything asked for has been delivered. No idea if there are gaps but if there are it clearly isn't on essentials. (Apart from their smartprice fizzy water, not been able to get that since start of Covid for some reason).
several retail chains have tried the centralised fulfilment model (warehouse or dark store picking) and although it's cheaper to make up orders that way (11% as opposed to 15%), in-store picking means faster deliveries, and uses less fuel. in a pandemic situation, in-store picking was the best way to manage the explosion in demand for deliveries. some retailers are actively decommissioning their dark stores.