I disagree with the statement:
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The actual answer as to why plugs are polarized in North America is found in a ubiquitous appliance: the screw-in incandescent lamp...All modern two prong appliances and office equipment are designed so that they can be plugged in either way and they just use the standard plug,
which happens to have the differently sized prongs.
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In my experience, lamp cords are the least likely to have polarized plugs. Electronic equipment such as televisions are the ones with two prong polarized plugs. They are also the ones to have warnings on the plugs that tell you not to defeat the polarizing.
