I’m pretty sure if Moses had had a wood chipper he would have used it too.
Moses was not ignorant of various ways of inflicting tortuous death.
Egyptians and other peoples of the time could do just about as good a job of it as we could today. It’s a process that hardly requires high technology. Burning, impalement, crucifixion, to name just a few, are all pretty low tech.
That Moses (or God, or whoever you think responsible for the Law) nevertheless chose to not inflict such deaths on criminals, unlike most law codes of the time, means something.