... the issue is you can't compare the stored energy in gas ... with a 150A at 2000V power supply ... If you spill a bit of gas as long as nothing is actively burning you just walk away and get something to clean it up, ...
But if it happens to ignite you can find yourself dancing in a heat source that exceeds the 22 megawatt level. For a short time, anyhow. B-b
If you are grounded and put 150 amps into your arm you could have some serious issues.
If you put 10 miliamps (i.e. one one-hundredth of ONE amp) up your left arm, or 30 ma between two contact points on your chest, or even a few microamps directly into the blood or inner tissues, you could have some serious issues as well. Like ventricular fibrilation. If there isn't a defibrilator handy right away, you're gone.
Available currents above that level are meaningless - all that matters is that the necessary tiny bit of current is delivered (while a larger current, big enough to cause the whole heart to contract simultaneously, is not). High voltage is an issue, but only because it is more capable of breaking down the insulating layers of the skin to drive the necessary current into a path that includes the heart.
Which is why I described a system that would keep the output power off until the exposed terminals are safely embedded in the car's receptacle, and shut down and crowbar the power supply output of the "pump" in time to protect a human body from electroshock if the insulation fails. Sort of the 300 kilowatt DC equivalent of a GFCI outlet, or a "bus differential" breaker control in an electrical substation (which actually has a chance of saving a lineman who accidentally hits a bus conductor with a metal ladder).
If you're not talking about direct contact between a body and the electrical supply, you're down two two other mechanisms: Arc flash and heating from wiring faults.
Heating from wiring faults is very comparable to heating from flame, and the relative power levels of the two sources is an apt comparison. In this case the higher power of the gasoline case, plus its ability to accumulate and burn at a rate only loosely related to the pumping rate, makes it far more of an issue than an electrical fault (which would also, no doubt, be quenched in milliseconds).
Arc flash does damage by light - ultraviolet, visible, and infrared, largely through heating - and by impact from vaporized material. This is comparable to the infrared from a flame and the flash and impact of debris from an explosive ignition. Again the relative available energy is germane to comparing the damage potential from the mechanisms.