yea but I have learned not to depend on it always being wired that way, as I found out the hard way with a red tag for reverse polarity at lamp sockets (ribbed wire to center), and guess what, the fixtures were made in lets say (to keep within the forum rules) the far east.You know how to tell the hot & neutral on a lamp cord, or you're amazed at how many don't know how?
Single,i got called to a house to trouble shoot an electrical problem on an addition. When i tore into the receptacles i soon realized the homeowner wired it with brown extension cord wire and had a refrigerator and window unit running on one circuit. He told me he didnt have the money to fix it right so i told him he owed me nothing and i couldnt help him so i wouldnt be liable when the house burned up. Didnt happen though. A year later a tornado tore up half our town and his was one of em.