This is rarely true. Only universally true for large corporate landlords where there is an entire corporate structure maximizing every dollar due to personal incentives put in place by executives/ownership.
Small landlords (yes, even those with 6 buildings) are almost never min/maxing rent like this. They are optimizing for other things like time investment and hassle factor. And even doing the right thing.
I've both rented and landlorded. In neither side of those transactions over decades was I either paying maximal rent or charging it. When property taxes went up as a renter, my small time landlord would show me the tax bill and I'd pay exactly the increase. Same went for when I had tenants.
I'd go as far as to say the majority of mom and pop landlords are not looking to charge maximum rent. They only start doing so when they have a problematic tenant they are trying to "manage out" of the unit.