With bicycle frames made by the thousands, there's bound to be some that have BBs that are not made accurately enough to perform adequately and there are some BB standards that are poorly conceived, with many early bearing failures being the result, like BB30. Finding those few frames made with bearing bores badly out of alignment does not say anything about the percentage of frames that may exhibit this problem, only that some exist.
Videos can be found showing frames with the bearing bores that are greatly oversized, but those bikes were ridden for a long time with the problem ignored.