It's not only mac's suffering from this problem. My old dell latitude with magnesium case had the same thing. I didn't fully understand why and some people thought I was mad for feeling it but it was there.
Only Apple is insane enough to make actual laptop chassis with unpainted anodized aluminum. Others either do it in plastics and/or painted metal. And paints are kind of liquid plastics.
It’ll depend on how well grounded you are compared to how well grounded the laptop is, where it’s touching your body, and your sensitivity to electricity which varies.