The Final Arbiter in Translation Services

Who is the final arbiter in the process of preparing translated materials? Is it the customer or the translator hired to perform the work?

If the issue is one of authority, the customer of course has the ultimate discretion concerning a translation they use operationally. The logic of customers is sometimes subject to question when the language judgment of someone internal to the customer’s organization is automatically given priority to that of a professional linguist.

Consumers of translation services purchase the judgment of professional linguists. That’s what professional fees for services buy them. If the language judgment of professional linguists is not given a higher status than the judgment of a non-professional speaker of a language, then what was the purpose to hire the professional in the first place?