> I knew a woman who couldn't eat chocolate because she found the amount of caffeine to be too high.

I think the causality went the other way in that case. I've been roughly caffeine free at certain intervals. Never felt anything from chocolate.

>If you truly detox from caffeine even extremely small amounts will be noticeable.

Maybe for a subset of people. Otherwise kids will be getting crazy jitters the first time they eat chocolate (presumably before they ever drank coffee/tea), which obviously doesn't happen.