Supermarkets make a loss on deliveries. They do it at scale, as efficiently as possible and with excellent IT systems. You can't compete with any of that.
So, £15 a time for a fortnightly shop? (£390 a year). I pay £5 a month for unlimited deliveries of orders >£40 from Ocado (£60 a year). Reliable one-hour slots, including early mornings, my favourites list and regular shop lists all set up, quibble-free refunds, freebies, offers etc. Plus the occasional £1 or £2 for a weekday evening delivery from a cheaper supermarket (£12 a year).
That £318 a year difference in fees is a month's worth of groceries to me.
Aldi and Lidl offer cheaper products than Ocado but:
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They vary. Half the point is the spontaneous bargain.
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£318 a year covers a lot of price difference, so would probably be enough to upgrade a regular Aldi shop to an Ocado one anyway.
Wealthier, busy people might pay more, for a more bespoke personal shopping and errand-running service; go to the farmer's market, the dry-cleaner, post office, deli etc. You'd have to build relationships so you knew what they wanted, when and how to substitute.
Aldi shoppers without cars might pay for the occasional shop but, once you've factored in your time, you wouldn't make anything.