What happened to the Rackets? (Frequency of encounter)

So seriously... what happened to them? Granted I don't spend all my waking moments stellarising but I do look back on quite some playthroughs now where no matter how many hundreds of years they went... the Rackets seemed to be 99 % absent from the galaxy. The two others, yeah they visit me every 3.5 months (or so it seems), always with the same crappy offers that I've turned down 37 times already, but the one caravan that (as I see it at least) has some interesting offers... has vanished into thin air or what?

Am I going through a streak of absurdly bad luck or has something happened to, dunno, at least the frequency of encounters for the three caravaneer groups?

For reference, the game I'm pausing right now to type this is in year 2490 and I've yet to see the Rackets even just once. If I had counted the encounters with the other two groups... I suspect that count would have reached 3-digit territory already.