If some manufacturers can advertise correct (or close to correct ) breaking strains (eg Sufix, Sunline, etc) then they all can (and should). Five or ten percent accuracy is good enough for me, but factors of two or more are absurd. IGFA braids get very close to the true rated load capacity. The current situation, where the angler often has no idea of the true load capacity of the braid, is ridiculous. And the terminlogy "equivalent to xlb mono" is next to useless, and should be done away with. Just give us an estimate of the true diameter, averaged for non-circular braids, and be done with it.
ps: "breaking strain" , although universal, is the wrong term for measuring the strengths of lines. Strain is a dimensionless measure of deformation, not load.