A good tech can display the signal traces from both O2 sensors simultaneously on an oscilloscope and see exactly what’s going on, even if it turns out that the wrong O2 sensor was used…the signal will trace out of spec. Let your fingers do the walking through the yellow pages and seek out a shop that can perform this level of diagnosis.
As to the second question, why does the emissions teat have to be based on such a silly thing, nobody can answer that one. We’ve discussed this at length ourselves, and the only answer is that it’s all politics. And revenue.