As people, we like to think categorically... especially "contracting" in the philosophical and legal sense. Whether its a medieval oath or a standard employment contract, the concept of "binding agreement" sorts out moral issues of consent and creates a platform for further relations.
Reality is generally less fussy about categorical boundaries. It likes spectrum. Linnaean classification is an approximation. Biology isn't strict about species, or even organism barriers. It's the same with a lot of cultural stuff.
On one end of the spectrum, we can have a business agreement negotiated diligently and in good faith between equal partners. On the other end, we have take-it-or-leave it agreements: The T&Cs stack a bank hands you when you take a loan. The wall of incomprehensible legalese we consent to when we use an app or website. An employment contract is somewhere on that spectrum. Employees may be able to submit "red line corrections" depending on their seniority and confidence, but generally its written by employers and treated as under their control.
In philosophy, contracts (including rhetorical ones like "moral contracts) are a popular mechanism for problem solving. They certainly are in law. In normal human life, norms are much more common.