These were channelers that obtained the apostille by going in person to the DoS. It was issued on the spot. Since the pandemics, the DoS no longer offer walk-ins, so the only advantage of channelers is that they can received your PDF, print it and mail it to the DOS.
In some States, there are authorized channeler that can request the background check and the apostille at the same time, and they are still quicker than doing it separately (LiveScan). This is an option only if the individual is still in the US and can go in person to the channeler's office.