I don't entirely agree with your view that this is clear cut racism.
We don't know for sure, but I doubt that the landlords in question are excluding certain races simply because they are of a certain race; I think it's more likely that they are excluding them because of the potential cultural differences they wish to avoid integrating with.
Well, it depends on how you view the term racist.
I'm push to see how it doesn't fit this pretty basic criteria (wiki).
Racism is behavior or beliefs motivated by racial stereotypes, it generally includes practices of racial discrimination, and ideologies of racial supremacy and hierarchy.
Some sources emphasize that racism involves the belief that different racial groups are characterized by intrinsic characteristics or abilities and that some such groups are therefore naturally superior to others, or follow practices that discriminate against members of particular racial groups, for example by perpetuating unequal access to resources between groups.
A bit like the age example. You don't state "no under 55's" because you just don't like people under 55 years old. You state it because you want to encourage a more mature type of tenant that that statement would typically attract.
Then would it not be easy to say, "mature tenant wanted" (in regards to behaviour) as opposed to partaking in age discrimination?.
Regardless of the motivation, specifying a criteria which excludes an entire social group based entirely on skin colour is racism.
I thought being racist was believing one race is superior to another. I don't see how that's racist. Seems like a preference to me.
Thinking one race is superior to another is in one form, but it's not the only indicator.
Denying one person which you allow another (based purely off race) is also.
Don't get me wrong, I don't think it can be enforced & I'm certain they will continue to do it by changing the language used if it was cracked down on, neither do I believe it's something the government can fix.
My point is, it's racism no matter how you spin it.