Panels and strips using more than 24V are extremely rare, with 12V being common and 5V existing for the hobbyist crowd. I've never seen a 24V rig for hobbyist uses (although some Ikea strips run there).
You don't wire them in serial anyways. In general if you care about blocks of LEDs at all you don't wire them in serial.
True for constant voltage, resistor limited current ones only. With constant current LED drivers, the voltage is approx 3V per LED. So it adds nicely to unsafe levels, albeit DC.
Another note is the power supplies can be quite unsafe too - esp. the cheap off-brand ones.