It comes down to money.
It costs a lot more to "sort" the cores to less percentage than that. Assume that they make 1000 cores at +/- 10%, and you want them to be 2%, so they sort them to +/-2%, +/-4%, +/-6, +/-8% , +/-10%. Assuming an even distribution for simplicity, you would only be interested in 20% of the manufactured cores, so they are stuck with 800 garbage cores ( in reality these get pushed to other people with looser tolerances). So you have to pay a premium for your batch of inductor cores. There are ways to get close while winding, or maybe add series resistance to the inductor with less DCR, but if you want a really matched set, IMO you have to start with the core.
FWIW, I've been planning on doing some "real" pultec inductors for months now, toroidal cores and all, and I'm currently waiting on a quote for +/- 2% cores... I was "warned" by the sales dept that they are going to be at least three times the price of standard cores.. But I'd rather have the assurance. I already have the winding quote, so I should have a feeler thread up this week, (check back if you're interested) since we'd need to get about 100 or so to meet minimums, etc.
(btw, which mfgs are you referring to? Are these "made-for-audio" inductors or plain old inductors from mouser etc?)