do you have a similar (or can borrow one) power cable?
maybe the insulation is not that good.
as you already know these power cables are shielded so no electric shocks at all.
you, i think already know that, you can receive a similar shock touching plastic or some other objects, the electricity is coming from your body.
P.S. Anyway keep on addressing this with apple. If you can find among your friends that in any room there is no carpet, not cold so you can be barefooted and try the same.