Sure, most do (and, yes, it’s easy to get your score these days, if you know how to go about it), but if one in four don’t, I don’t think it should be surprising if some applicants for an apartment wind up unexpectedly failing their credit checks, even if they’ve been told ahead of time what the minimum credit score will be.
We’ve got a lengthy thread here on the board about why financial literacy is such an uncommon thing, and not knowing your credit score (or how to go about even finding it out) is probably part of that.