why is it that when you buy a pair of socks you get two but when you buy a pair of pants you get one item?

Answer 1

It is because it is meant for two legs, not 1

Answer 2

Maybe because back in ye olden tymes (the Middle Ages), men's stockings (which eventually, over the years evolved into pants) were two seperate legs that tied together where the fly and back seam would be on a pair of pants. Eventually, they were sewn together. Perhaps calling them a "Pair" of pants comes from back when to assemble the garment, you needed a pair?

Just a theory.

Answer 3

Some nouns have no singular form. Such a noun is called a plurale tantum:

annals, measles, nuptials, thanks, tidings, victuals, vittles, credentials

Neither do some names of things having two parts:

pants, scissors, trousers, tweezers

Note, however, that these words are interchangeable with a pair of scissors, a pair of trousers, and so forth. Nor are scissor, trouser, tweezer, or pant the names of the individual parts. However, the fashion industry frequently calls a single pair of pants a pant; this is a back-formation. (see also more discusion on Plural to singular by back-formation in the link below.)

Answer 4

Maybe because it takes two socks two cover up two feet, but only one pair of pants to cover up two legs.

Answer 5

the pant bit is the legs and you get two of them