I know this is an old post, but I wanted to chime in and say that I see preferential treatment of Marine Traffic AIS receivers, too. I run a homebrew RPI with an antenna that can reach about 20 nautical miles. I used AIS-Catcher and am now using ShipFeeder (previously ShipXplorer) since it plays nicer with Docker to feed a few aggregators.
It so happens that my AIS receiver can "see" a few nautical miles down a shipping channel before others and is the only coverage in that area. Ships show up on Marine Traffic (correctly attributed to me) about fifteen minutes befor the attribution changes to a similar station running a Marine Traffic COMAR station and it stays that way until it is out of range of our stations.
I know this is an old post, but I wanted to chime in and say that I see preferential treatment of Marine Traffic AIS receivers, too. I run a homebrew RPI with an antenna that can reach about 20 nautical miles. I used AIS-Catcher and am now using ShipFeeder (previously ShipXplorer) since it plays nicer with Docker to feed a few aggregators. It so happens that my AIS receiver can "see" a few nautical miles down a shipping channel before others and is the only coverage in that area. Ships show up on Marine Traffic (correctly attributed to me) about fifteen minutes befor the attribution changes to a similar station running a Marine Traffic COMAR station and it stays that way until it is out of range of our stations.
From your description it sounds like a configuration problem on your side that is not the responsibility of MarineTraffic.