> There isn't any reason for it to be adversarial, it's certainly not inherently so. Only if one or both sides want to make it adversarial.
Landlords compete with their potential tenants for houses to buy. When landlord driven price increase, it prices out people from buying a home/flat, but they still need a roof over their heads. So they rent. This gives landlords cash needed to buy more houses/flats. This also keep rents up as landlords pay more for buildings. So tenants are less likely to accumulate cash for loans/something else. From small owners to big corporations it is a vicious cycle.
The landlord also takes on risk and responsibility here. Like any business, if they do a shitty job they go broke. If they do a good job, they make bank and expand their business.
There isn't any reason for it to be adversarial, it's certainly not inherently so. Only if one or both sides want to make it adversarial.
It is supposed to be a win-win scenario. Some people prefer to rent instead of buying, so they need a supply of rentals and the owner needs someone to live there so it doesn't sit empty costing them money.
Fortunately I've never had one of the adversarial landlords. I paid them on time and took good care of the property and in exchange they have been super flexible and let me do whatever I want. That's a win-win.