Must admit I do find it surprising when I hear the anti Tesco stance.

Does seem to be a case of biting off your nose to spite your face unless you are very well off in the miles earning department. After all a named bottle of wine or tin of beans is just the same if bought in Tesco as it is if you buy it elsewhere.
If I knew it got me some extra miles I wouldn't let my feelings against the store stop me from buying it.

FWIW when I was in the UK our local store was a Tesco so we did most of our shopping there and found the staff to be amongst the most friendliest of all the stores. Maybe it depends which area you live in?