In North America, business is built on the idea that 'the customer is always right.'
Literal
North-America [in-では], business [topic-は] 'customer [topic-は] always right' [quotative-という] idea [of-の] foundation [at-に] is-standing.
のもとに ('on the basis of, under') is a formal compound meaning 'based on, founded on.' 成り立つ ('to be composed of, to be formed, to hold [as an argument]') is a formal verb for structural composition. The quoted English business maxim is rendered verbatim in Japanese — classic cross-cultural adage.