Being poor is a huge disadvantage; you have that absolutely right.

But there's still plenty of room for institutional racism. It's very easy to do. First, notice a feature (geographic, usage-pattern, whatever) that differs by races. For instance, maybe a lot of black people live on the west side of the river, but not the east. Second, think up some perk or detriment. Like, the East River Library Renovation Project, or West River Parking Fine Increase. Apply your perk/detriment on the basis of the feature, not explicitly on the basis of race. If you're particularly paranoid, come up with some excuse. ("A review of parking compliance revealed low levels in West River," or "this is part of our 5,982 year plan to review all public infrastructure and fix white-used facilities first while ignor...um...OOPS, I mean we can't do everything at once, right?") Ta-da! You benefit one racial group and disadvantage another, and since there "is no institutional racism" you don't get called on it.

It's easy! (And unjust!)

And that's even before considering the cascading effects. "Well, institutional racism made this majority black community poor, but now that we are totally away from racism, we don't do that. We strictly fund local services from property tax revenue in that neighborhood, completely impartially. No problem here at all."

Of course, it is also true that a lot of people just look at overall trends and assign blame to racism within the institution they're looking at without having the foggiest idea whether it's actually true. They just assume: see difference in X, therefore X is wicked.

Don't do that. It's stupid, unjust, and won't even fix the problem.

But that people do stupid stuff and argue wrongly doesn't mean that institutional racism isn't there and very real. Only that you have to use your head when someone cries that it exists.

If the boy is crying wolf, don't assume there must be a wolf, and don't assume he's lying again. Go see if there's a wolf.