I suppose you could have a landlord-specific-union. If I own and rent out 3 houses then I’d just evict all 3. If I owned 50 houses, I could just obfuscate true ownership through various LLCs. If you didn’t know all my properties, you couldn’t form any meaningful union against me. Apartment complex would be fucked though.

What does a strike look like? Everyone moves out? It’s not so easy to just stop renting.