They aren't unique.
None of my 6.4's have consumed any discernible oil between changes either.
What one has to consider about catalyst poisoning is that it's cumulative. It's like lead poisoning in the body or mercury, it doesn't get processed out. So, if you are consuming enough oil to kill the cats with phosphorous, whether it's 700ppm or 1,000ppm, the end result is the same, you'll reach that fatal concentration at some point. Would be easy enough to toss this into a spreadsheet and compare the two, but consider federal emissions warranty requirements and allowance for oil consumption by OEM's for "acceptable" as well as the pretty low bar set by the API for performance and it's pretty easy to read between the lines as to why API phosphorous limits for xW-30 oils and below are so low.
For Euro approvals, the quality of the oils is higher, because the approvals are more stringent, and so we aren't seeing the same crack-down on phosphorous as we do with the API despite the prolific use of GPF's. Even for light oils like M1 ESP X2 0W-20, phosphorous is at 880ppm, above the API limit, while EP 0W-20 is 760ppm. EP High Mileage is right at the limit at 800ppm.
And note that xW-40's and xW-50's are not required to have low levels of phosphorous by the API, it only applies to lighter oils.
