Parking schemes seem to be down to local authority whim. Our Sainsbury's , right in the town centre, operates a Pay & Dsiplay car park in which the tickets are redeemable against goods. Tesco & Waitrose are both "out-of-town" and have their own car parks. No-one would have any other reason to park there. The Sainsbury's car park is almost certainly used by others - quite often if we needed something from the High Street or to go to the bank, when Mrs. Wow and I still shopped by car, she would go round Sainsbury's with the parking counterfoil and I would rush round the other shops. Now, on the rare occasions I go to Sainsbury's I take a Brompton and wheel it roundthe shop, using its front bag as a basket.
I wouldn't dare leave a decent bike outside Sainsburys. I don't think there are any nearby sheffield stands, and tehre are lots of oikish yoof hanging about. I've never sen any at Waitrose.