Use WD-40 for starter fluid, never use starting fluid. Starting fluid burns too hot and can damage the rings. WD-40 is what they teach mechanics to use in small engine school.
Yeah, you’re right. That car starter stuff is ether, isn’t it? Highly combustible.
It’s why I never loan my truck, my chainsaw or my wife: you can bet some SOB will throw a rod in any one of them.
If you've got a mower with one of those little vacuum-operated fuel pumps on it that dries out and loses prime over the winter, you can get the mower started with a propane torch. Unscrew the tip and pull that little "pill" out of the stem and set it aside. Open the valve up all the way, stick it down the carb throat and turn it over. It'll start right up and run on the propane until the fuel pump gets the carb filled back up.