1000 PIC is not the same as 1000 TPIC. Several ACMI only list it as a 1000 PIC, unlike the legacies which list 1000 TPIC....
Several LCC’s actively recruit senior regional FOs and junior CA’s that do not have the 1000 TPIC the legacies prefer. It keeps them at the LCC to upgrade, get their hours, and then move on to a legacy before becoming an expensive senior CA. That is happening to a lesser degree now that the LCC’s pay almost as well as the legacies.