I didn't base my definition of racism/xenophobia on the personal bigotry of those involved, to the contrary, I explicitly mentioned that most probably some of the measures now in place that look like bigotry from the outside have been probably put in place for material (i.e. money/financial) reasons.

In the case I mentioned, most probably that real estate agency lost money by dealing with Romanians and Poles in the past in a different way than it's used to lose money by dealing with local British people, that's why it put in place more complicated procedures for Romanians/Poles than it has for the locals. Yes, it is discrimination, but, again, in many cases it is based on pure material reasons, i.e. people not wanting to lose more money than they have to.

Is there a distinct form, application, and process for Romanians/Poles? Or is it just "a lot of tenants have caused issues in the past, so we have a bunch of checks we perform before we hand over the keys to a £250K piece of property?

I feel like that's an open-and-shut case if "Oh, you need application form A1234-v-Romanian/Polish" is the case.

As far as I could understand from my friend, as a non-British resident she has to be present in person at the agency for a specific step of the rental process, and as far as I understood from her that “being there in person on a set day” step isn’t applied to British citizens. If true (it is possible that she might have gone things wrong, who knows) that could be seen as a “visual vetting for non-citizens” process.

Again, that seems to be specific to that big agency, she also told me that in the past when she and her SO had found rental arrangements through smaller agencies things were a lot more straight-forward.