The difference is that Tesco are manufacturing and importing food, which is basically unlimited in supply relative to UK demand. Landlords are buying up supply. Also food is fungible, unlike say homes for someone working in London.
The supply of properties to live in is very strictly controlled in the UK and it's not comparable at all.
"Landlordism supplies shelter to those who cannot or don't want to get a mortgage. People need choice and if the only landlord is the council then people won't be able to find accomdiation quickly."
That is because landlordism PREVENTS people getting mortgages. We have far too many landlords now. Compared with 20 years ago, home ownership has fallen and private rental increased, and this is because there are now so many more buy-to-lets.
It doesn't constitute 'choice' when your only option is to rent off a landlord.
Buy-to-let is a bad thing.