The first major evacuation event that hits a primarily electric-vehicle city is going to sorely test that idea. Batteries need to hold about 3-4x the charge that they currently do to make that plausible without endangering thousands.
You won't consume fuel while at a dead stop in the traffic jams. You'll have peak efficiency when moving at low speeds in the traffic jams. You'll already be charged up at home, while everyone else will be waiting in line at gas stations to fill up. Some people won't even be able to get gas, because the stations will run out in the rush.
Vehicles travel for hundreds of miles in the event of a major storm. Some places may be up to 6 weeks without power upon returning. So you drive your battery powered car back home, and now it's dead, and you have no way to recharge it. Guess what you're going to be relying on to get basic essentials given that FEMA vehicles are NOT coming to you to deliver food? Someone else's ICE.
So when it's 100 degrees and 90 percent humidity outside and your neighbors with the ICE vehicles have gone to the gas stations for refills to both their vehicles AND their generators so that they can run a portable AC unit, you're utterly out of luck with your electric paperweight. I suppose you have a shot if you still have working solar panels, but in the situations I mentioned... LOL. Even if the winds don't shred them, the debris will.
EVs should be more efficient when driving at low speed than an ICE car, and the regenerative braking in stop-and-go traffic will help reclaim some wasted energy.
EV's don't expend power running the motor when stopped in traffic. Most ICE cars out there do not auto shut off their engines when idling (it's fairly recent that many newer cars have that feature), and even those that do need to turn the engine back on after a few minutes in order to run the car's electronics.
For the people who can charge at home (admittedly, there are many who cannot), their cars will likely already be fully charged when the evacuation order comes down. And we already know what happens with ICE cars when there's excessive demand for fuel: hours-long waits at the pump, and gas stations that run out entirely.
This would not be possible on ICE vehicles, IMHO.
It gives us a choice/warning right? Because sometimes I'll stop charging so it doesn't trip the breaker as I run something else.