60 volts is nothing UNLESS you are completely wet or sweaty.
"It is estimated at 150 ohms for completely wet skin (in water), 1000 ohms for sweaty skin, and 100,000 ohms to 500,000 ohms for dry skin."
Assuming a worst-case scenario with dry skin providing a resistance of 100,000 ohms, fatality becomes a possibility if the current exceeds 50 mAmp.
Therefore, the lethal voltage would be above 0.05 (50 mAmp)×100,000=5000 Volts. [1]
So if you are wet or sweaty, it could be 7.5V to 50V that gets dangerous.
So it makes sense why 60 volts is a safety threshold, especially for those that live in Florida or Arizona.
[1] https://www.scienceabc.com/humans/how-many-volts-amps-kill-y...