A disabled person’s perspective: long post.
I get around with a stick, sometimes needing two, but legally, I can’t walk. So I can’t go and do a supermarket shop. I shop online, getting a big delivery once a month. I’m single and retired, and rarely buy processed food. Cakes, biscuits, pastry and sometimes bread, I make myself. I don’t eat salty and oversweet processed stuff, I can taste it and it’s disgusting. I have time to make what I want. I’ve learned to cook late in life and I like it. My friends seem to like it too. 
I plan my meals, cook it, freeze what I need, eat it.
Currently, I prefer Waitrose, but I’ll be moving to a bigger town 100 miles away in a few weeks. I might explore what other supermarket chains have to offer in that area, or I might stick with Waitrose. I checked the postcode for Waitrose deliveries, along with broadband coverage and flood risk before I put in the offer on the house. I particularly like certain of Waitrose’s own-brand stuff, especially the pasta. I always check the offers and have favourites marked.
The quality of shopping online is inconsistent between different branches of the same company, like bricks and mortar branches of the same company vary. Waitrose gives me a far better online shopping experience than Sainsbury’s (consistently bad, wrong items delivered, fail to make delivery on the day at all, too often); Tesco (far too many own-brand only choices). Neither Aldi nor Lidl do online grocery shopping; online is a very recent invention by Morrisons but what I’ve bought in store when a friend has taken me there, hasn’t persuaded me to try it. Maybe I’ll give them another chance when I move. I won’t shop at Asda, ever, because I don’t like the hugely exploitative way the Walmart outfit operate globally.
Waitrose are consistently excellent in prompt delivery, more expensive substitutes (rarely necessary) are only charged at the price of what I actually ordered; availability of branded products if I want them or their own brand are usually excellent – baked beans are highly recommended! Deliveries are on time but they phone me if they’re going to be late for bad weather or something like that. I’ve tried branches of each supermarket in the three areas I’ve lived in while online shopping has been available.
I have two freezers so I can freeze as much as I want. Milk and other dairy stuff, and bread, freeze well. I just wish Waitrose had a butcher that delivers marrowbones (for stock, not a dog), but you need a proper butcher locally for those. Fruit and veg are the only things I need to get out of the house for between deliveries, plus the occasional thing I might have run out of and not anticipated needing just then.
The upshot of all this is that, for me, Waitrose is no more expensive than any other accessible supermarket although I’ll always go to a real butcher for good meat if there’s one locally.