I won't speak for SE, but I'll speak from a parallel experience.
Y'all know who the "first online auction site" is right? Well internally they have immunity policies for Powersellers that the regular sellers and buyers didn't have. Some of the largest Powersellers that are akin to RMT bots, eg the ones that *auction site* was selling counterfeits but could do nothing about unless a DMCA claim was filed by a verified rights owner. Basically such powersellers did so much business that "losing one" due to erroneous complaints was considered a last-resort. Because when an account is suspended, someone could literately be losing thousands of dollars an hour. So the internal policy was closer to "phone PS and tell them their account will be suspended if all of brand X item isn't voluntarily removed immediately"
Like in that case, the reason they can't get rid of accounts easily is because it becomes a PR nightmare to even have ONE mistake. That's why people continually see fakes posted to the site, because not enough people report them, and IP holders tend to just "batch" report once a week, giving many listings too much visibility before they are removed.
So in the case of SE and FFXIV, it's likely that some of these RMT accounts have been around since launch, with level 50 characters, and suspending them immediately isn't an option since there's a possibility it's not a bot. The Spammers however, are clearly abusing the free trial system, so there is no money lost in immediately suspending such.
In SE's case, it's likely we see the bots because many of us have resigned to the fact that they will never get rid of them within 5 minutes, even though SE has shown they can respond to a ticket within 5 minutes (when you report someone for griefing,) they never do so with the cheating reports, not even acknowledgement that the ticket has been worked.
Like that missing feedback mechanism is something Archeage kinda-sorta solved. You could report up to 5 bots (a lot of good that did when zones would literately have 100's of them) and as long as the ticket had not been worked, you couldn't report more. At some point they would batch nuke the accounts that were botting and you'd get a bit of a reward for doing so in your inbox. But the time frame from reporting to an email would sometimes be a week. So during that time a bot could have got to level 50. Unfortunately it was impossible to report "spamming" bots in that game because the report mechanism required 5 reports in a 24 period for the automatic anti-bot system to do anything... which it did nothing. There was also a provision in the game to allow "good" players (eg ones that weren't pirates/criminals) to kill reported bots in "safe" zones, but wasn't actually enabled.
Like the one thing I wish every MMO would do, is allow the PvP mechanism to kill bots. I don't care how much like griefing it looks like, but if you provide a "Engage PvP (Suspect bot)" mechanism, so that killing the bot forces it to respawn in a "jail" somewhere it can't teleport from, can't shout/yell/say from, makes it vastly easier for GM's to count the bot activity. Because a real player will actually respond to a PvP fight by fighting back or running away, while a bot will just stand there and die, because even if it has PvP countermeasures, I've never seen a bot win against a real human except by being overleveled or ganged up on by PvP combatants. (Which to be fair is a problem in PvP... period.) But in the case of Archeage, the bot activity was extremely out of control (same software people use on FFXIV) to the point that there were hour long queues caused by bots having a higher population than actual players.