Yep, that's the one I was looking at. In any event, formulation of a lubricant involves considering all kinds of different objectives, and they don't always coincide. The EPA doesn't seem terribly concerned about phosphorous content in oils, per se. However, automakers are required to guarantee their emissions systems for fairly lengthy terms, and higher phosphorous oils (or higher SAPS, or higher SA, or whatever the case may be, given the type of emissions system) can be problematic for catalytic converters. So, lower phosphorous oils helped address this, and the manufacturers wanted that more than the EPA did, since the manufacturers have to underwrite their warranties. The EPA doesn't do it for them.
Concerns about different emissions systems target a few other compounds in oils, and have different oil specifications. Look at the ACEA C type oils. Also, different fuels and different fuel specifications matter. HDEO specifications evolved in no small part due to the introduction of ULSD. TBN actually crept down a bit in PCMOs and HDEOs for a time period, but the big names are up there, meeting ACEA specifications in both A/B and E sequences. Of course, the ACEA C sequences are different, and we see different additive packages.
Note that there are plenty of non-ILSAC oils and non-API oils out there that do have plenty of phosphorous. There are also low phosphorous oils specifications that have nothing to do with anything in North America whatsoever, such as ACEA E6, which may or may not coincide with an API CJ-4 certification.