One thing comes to mind, maybe they are attacking bigger population systems. They wouldn't be part of the pilots federation and more than likely wouldn't bother with human ideals or protocol. They would just see systems, aliens and tech that's it.
They are a advanced species that started attacking us after we invaded there property in the Pleiades nebula. Once they learned enough through scanning theyve started pushing into our area of control. They mustve realized by now that attacking our space ports isnt deterring our attacks against them.