I think we still need more time/data to get the whole picture. EVs are still in their early stages.

It would be interesting to look at fire rates for vehicles at rest. These types of fires have the potential to become quite serious, as they are often not immediately noticed, especially if the vehicle is parked in a garage or remote area. This additional time allows the fire to spread and intensify.

Since EV fires are typically more intense than ICE vehicles, we should expect EV fires to cause more damage to the surroundings and to spread faster. Though, this danger could be offset if EVs have a lower probability of self ignition.

We should also look at fires while refueling/charging. Lithium cells are most dangerous when charging and discharging. While an overfilled gas tank is easy to spot and may catch fire, a continually overcharged battery is invisible and will catch fire. Also, because of the long charge time of batteries, many EV owners leave the vehicle unattended while charging and would not immediately notice a fire if one were to occur. In addition, EVs are often charged at home, in close proximity to residences and other vehicles, and often within garages. These residential locations do not have the same fire safety requirements and suppression systems as gas stations, so a vehicle fire at home is already much more dangerous and has the potential to severely damage your home.

We have had a century to figure out ICE, but it's still very early days for EVs, so only time will tell.