But reading RAS I got the impression that partnerships are not common
in the US (hence the interest of many US pilots in cheap - or shall I
say low-budget? - gliders). Is my impression correct?

A club member put it to me like this recently: "In this part of the
country (Northeast US) there are only a handful of truly great soaring
days per year. When those days arrive, you don't want to be sitting on
the ground while your partner flies".

Tony V.