Basically as I outlined. So long as you are not publicly discussing using mods or plugins, and are not leaving a trail to follow - such as linking your Twitter account where you post tons of modded screenshots, to your in-game character name and server (yes, people do this, and it’s stupid lol) - then they genuinely cannot detect if you are running anything, and thus cannot issue you any sort of punishment.
This is only possible if you leave a trail. And even then, it’s not always guaranteed; oftentimes SE is very 50/50 on whether they take outside evidence into account during reports, so even if someone tried to use someone’s mod-showing Twitter to maliciously report them for breaking ToS via modding… if the player has nothing directly linking their Twitter to them in-game, it’s not likely that any action would be taken.
No idea. I don’t play anything besides WoW and Diablo 4. Diablo 4 doesn’t have anti-cheat software in it, to my knowledge.
There is no evidence they have anti-cheat software in their other games. And if they do, it isn’t the malicious malware-esque type.
And even if they do have some sort of software like that - there is no reason to implement it in WoW, at all. The game is almost 20 years old and addons have been used since almost the first year; they’ve had plenty of opportunity to change their mind about addon usage and do something to clamp down on it, and they continuously choose not to.
And again - there is zero reason addons should be banned. Especially ALL addons - including stuff like TRP or Handynotes, which doesn’t even affect people’s gameplay in group environments. I don’t really see why you or people like you are so invested in trying to rip away customization tools or helpful QoL just because you, personally, have a vendetta against using them yourself.
Play how you like. Let others play how they like.