The driver gave me a receipt which shows a lower amount.

We connect you with self-employed delivery drivers who visit a supermarket such as Tesco's, Sainsbury's, etc. and shop on your behalf, buy the products and then deliver them to you.

Your delivery driver time to visit the supermarket, buy the products and deliver to you. Of course, no-one is going to do that for free. Therefore, the price you pay is more than the supermarket prices to cover this. The majority of this extra money goes to the delivery driver who may be a taxi driver or a self employed courier.