They are actually asking for less than BTN or SECN get, but Directv doesn't think it is worth what they're asking. Even ignoring stuff like the lower ratings of Pac 12 games (because of time zones among other reasons) it doesn't make sense for Directv to pay much for Pac 12 Network because they've already lost all the subscribers who consider Pac 12 indispensable. Some might switch to Directv if it was available, but not enough to make it worth paying what Pac 12 wants as far as Directv is concerned. Most cord cutters are leaving due to price, adding a channel that 90% of people won't watch that adds a buck to the price for all west coast customers isn't a sound business decision in 2018.
Pac 12 can't offer them a better deal because they included "most favored nation" clauses in their other contracts, so if they give it to Directv for less, they have to give the same reduced rate to Dish, Comcast etc. Then there's the complication of this ridiculous business of having seven full time channels instead of just one and a couple part time alts like BTN & SECN.
AT&T apparently has some sort of contract with the Pac 12 for networking services on campuses or something like that, and maybe taking Pac 12 Network will be required to renew that contract. Or maybe AT&T will walk away from that rather than pick it up. But that's pretty much the only hope of seeing Pac 12 on Directv until the existing contracts with other providers expire, and I wouldn't hold my breath even then.
Pac 12's main problem was the stupid idea to go it alone, instead of partnering with a big company like BTN did with Fox and SEC did with ESPN. They have no leverage, whereas SECN got coverage all over the place right away because cable/satellite companies have to bow before the Mouse