I worked for a company that happens to make electrical tools as a small part of their huge tool line. If your trying to guess, you probably don't own any of their tools unless you were a professional Mechanic or racing buff, starts with an S and I am lucky to have a bunch of them, thanks to my employment there.
I was involved in several redesign projects on these tools (sourcing guy, but have a Metallurgical Engineering degree) and I understand how and why they are tested in a certain way. Bottom line, you would be SHOCKED (pun intended) at how far a fairly low voltage like 110V can jump across a gap. Yes, in most cases that acetate (the clear ones) or the Nylon ones (the others) will protect you, but not always, especially if you are well grounded. I have several screwdrivers rated for 1000 volts (they have woven composite shafts and are tested at 10,000 volts grounded in water) and I still call an electrician. I am sorry but my life is worth more than that.
Bonus fact for fun - the clear handles are made from Cellulose Acetate which is made from Wood Pulp.