Japan runs at 100V, the lowest and therefore safest voltage in the world.
100V, 240V, if 15 amps runs through you, you’re having a really bad day either way. That’s another way of saying, “it ain’t the volts, it’s the amperage.”
100V, 240V, if 15 amps runs through you, you’re having a really bad day either way. That’s another way of saying, “it ain’t the volts, it’s the amperage.”
So given relatively constant resistance, voltage is linearly proportional to amperage. Double the volts, double the amps.
The resistance of the human body can vary, for instance, if you're sweating, your resistance drops, therefore the amperage increases. Dry skin has high resistance, so if you stab electrodes through your skin and into your flesh, the low resistance of your mostly salt water body will carry a high amperage. But with all environmental factors being equal, if one person gets zapped by 100V and another person gets zapped by 240V, the person zapped by 240V will have 2.4x the amps running through them, and their day will be roughly 2.4x worse.
In other words, sure, guns don't kill people, bullets kill people. But you'll find that whenever a bullet kills sometime, there was probably a gun involved.
A 12V car battery can kill if you’re not careful.
A 12 V car battery can kill you, if it has a low-resistance path that goes through your heart. Touching the terminals will do nothing. Maybe if you applied that voltage to conductive spikes inserted into specific points of the body, there would be some effect.
A voltage source, like a car battery, does not determine how much current passes through a circuit. That is determined by the circuit's resistance, and the source's upper limits (i.e. internal resistance for batteries, rated current for power supplies).
As voltage increases, so does current. High-voltage supplies will absolutely kill you, as long as they're able to supply the required current. Which, to harm a human heart, is quite low (tens to hundreds of milliamps). Aside from fringe sources like static electricity and tasers, most HV sources are entirely capable.
https://hypertextbook.com/facts/2000/JackHsu.shtml
I recall a story, late 1990's to early oughts, of a solo researcher found dead in his lab of apparent heart failure whilst working with very low voltage- and amperage currents, but at critical frequencies. I cannot find an online reference presently.
Amps are a side effect of the thing that is killing you - volts.
The only time a voltage sufficient enough to kill you, doest kill you, is when it is only present for an extremely small amount of time and/or not traversing your heart.
The reason this is the case is because your initial premise is incorrect. Power kills you. Power equals work divided by time. This is why huge voltages over short periods of time don’t kill you.