No that is not how high voltage works 74, it will shoot out at some points and yes some fires will happen but not all the time.
The same amplification and reversal of power will go throw all wiring, some appliances may explode or just melt down, A/C unit compressors may explode.
It all depends how high the amplification of power is. If we know it will fry all electronics in cars, homes and building we also know that this means there will be a high amplification of voltage which some wires will not hold up to. I see this all the time with small electric high voltage which kills the electronic appliance and I have found a wire burned out. So you can see a very high amplification of voltage of an EMP or Solar Flare. Some home wiring will hold up but cars and truck wiring is not as strong. I have seen this in cars that have had a short and the wiring somewhere fried were it had to be found.
Also remember that many building are very well grounded for lighting so there maybe small fires but not that many. Also the systems in homes and building are made to turn off, the electric panels breakers will trip.