At least they tried to trim it. Many others just push the AP without even bothering...
I bet that the reason for a wrong trimming is that they are not using the rudder at all. I have seen many pilots center the beta target without pressing the rudder. And many, also, use the trim control incorrectly, in short "bursts", when you have to keep it for quite a few seconds before you feel your leg unloaded.
If they don't use the rudder at all is easy to get confused to which side the A/C must be trimmed, specially if the yaw damper is doing most of the job for you.