Does some kind of magnetic resonance cause wires/cords to always become tangled ?

You may be onto something here. If, as an experiment, I put two cords down next to each other and go to bed at night they are always tangled in the morning.  If you carefully coil up several cords and stack them in a box they create the Gordian Knot.  There must be some rational physical explanation.

No.

It's careless plugging and unplugging

and

careless moving around of plugged-in items.