No the rules of physics aren't different. Regardless of amount of voltage, it's still on the ground. Think for yourself if you step on an OPEN teared apart 110V cord? If safe and you don't hold anything in your other limbs, the current finds another lead, and ground at the other leg. It's really NOTHING different at all. Law of physics works the same. That you get electrocuted by the real lightning spreading out in the fields, on the ground doesn't matter. On stage you get zapped, and may survive. Mrs Welders didn't survive. It's the same principle. However, if you hold anything else grounded in your hands, like a vocal microphone, you're equally as toast. If you should carry out some wild stage antics that is part of your stage show, like kneeling and go down on all four, you bet that that the current from your toes finds its way throughout the arms, and through the body. Since this is regardless of barefoot or not. Let's just say avoid barefoot for a large number of other reasons than the step potential or current.
In a lightning strike of a thunderstorm the area is around 4 km and more, but on stage a few meters. The source of the voltage/current is totally irrelevant. If your stage or power grid looses ground, it causes stray flow, since the current can't find a rigid line to follow. People thinks "well it's earthed, and ground and since the current exists in the ground, it can't creep up into anything". It's not only outdoors during lightning, but country houses several miles away can get step potential in the house, regardless of no matter how well the house is protected from real direct lightning strike above. No matter how much "faraday" cage the house is built, lightning conductor, RDC's it can creep in and fry your computers, cell phones on charge, tv-sets, kitchen gear, whatever, and it can cause you yourself to get zapped, inside that house. Barefoot or not. But if you live in the house and are barefoot in the bathroom shower (most people are anyway) and you happen to be exposed to some current from a lightning strike far away, you better watch out carefully. If that happens you're pretty sure of being zapped quite seriously, from the metal pipes that goes into the shower from outside. No RDC's or lightning rods, or faraday cage constructions will keep this from happening.
Truly Lucky on that one.
