retired Union Carpenter / woodworker all my adult working life.....own/owned just about every type and brand of woodworking tool there is at some point in my life. just about every one of them has it's switch replaced...some of them, more than once.. and it's not from misuse or poor handling...... some of my machinery and tools that are just about as old as I am and they all work as good as new. they don't get that way from abuse. all my tools are good, well known brands, .......Porter Cable, Milwaukee, older Black and Decker, Older Rockwell, etc.
what makes you say that the human is the weak link,.....forgetting to turn off a switch is not part of the circuit and it is just as easy to forget to flip a switch as it is to forget to unplug the battery.....I have used switches on my planes , too.