Low margins just means big corporations have th advantage, because they make profit through volume.

If renting wasn't profitable at all, landlords wouldn't rent.

And in many cases they don't. Which is one reason why ten percent of US houses are vacant.

But that misses the point, which is that housing should not be a for-profit industry.

If you repair a house, if you maintain a house, if you renovate a house, you have the right to be paid for your labor. Any profit you "earn" from rental payments, above that amount, is money you didn't earn - it's money you were able to extort from your tenants because you have a piece of paper saying you own the house and your tenants do not.

Whether a landlord makes $1 profit or $10000 profit, that profit is still "earned" by collecting rent on property, not by creating any value for anyone.

Housing is a human right. And rent collection is theft.