It's not "obvious" though: there is no proof that your electron didn't (via tunneling) exit whatever trap you put it in only to get replaced by some other elect

It's not "obvious" though: there is no proof that your electron didn't (via tunneling) exit whatever trap you put it in only to get replaced by some other electron from the environment which jumped in a short moment after (also via tunneling). The best you could say is "it's highly probable that at least at one time it was at least a two-electron universe."