One thing that may work.
Sit down and work out with him how much he spends on the car per week.
Include everything, insurance, repairs, MOT, tax, petrol, and money aside for a replacement car, etc etc.
Then work out how much that is per week.
Then work out how many taxis he can take within his town for that money.
So, taxi to supermarket £5, taxi home £5 is still less than the cost of the car.
Also, found out today, Morrisons do this service where you can phone up and tell them what you want instead of doing it online. So my friend's mum phones up, has a chat to the person on the phone, reads out her shopping list, and they convert it to an online order and it gets delivered. No online shopping necessary.
Practically, is he close enough to use amobility scooter instead? That woudl keep him independant.