It's not even a consistently American thing.

I (from Texas) use "couple" to mean two-ish-or-more whereas my wife (from New Mexico) uses couple to mean exactly two.

I use "couple" to (roughly) mean "just enough in small amounts" like:

- just a couple more minutes (obviously doesn't mean 2 minutes and 0 seconds)

- grab a couple of glasses (probably two unless there are three people)

- buy a couple of things (I'm making a short trip for a small number of things)

For those decrying using imprecise language, it's because these are scenarios where enumerating would give an incorrect level of precision.