Here's a case where GFCI saved my a$$. I had a commercial, 120V, off the shelf, UL listed hotplate that I used under my mash tun to help maintain heat. One day, after about 10 uses, it developed some internal open and placed 120V main directly on my SS mash tun. The tun was isolated from ground and had no leakage that the GFCI could immediately pick up on. I did not realize this until I made full contact on this tun and the GFCI popped as designed, only after a very brief holy s*** moment as full 120V ran from one hand, through my body, and heart, to the other hand resting on another pot that was thoroughly grounded.
I am not a commercial electrician but do have background and schooling in both AC and DC electronics and understand the concepts fairly well (in my youth I fixed common household electronics including televisions with 15kv+ 'flybacks').
Going without GFCI and any other safety technology on any such brewing equipment is simply asking for disaster only to save a few bucks. Just don't do it. 120V AC will kill you in an instant. It is irresponsible to suggest that anyone reduce the presence of safety devices to save a few bucks because some unrelated and carefully tested commercial devices may not have those same devices (and yeah, BTW, the electric water heater I just installed 3 months ago had a GFCI built in).
Brew on, safely