In the US "at will" employment in many states means that companies don't ever need employment contracts. Jobs have terms and conditions, often these are explicitly not written as employment contracts and you never actually sign them, you just agree to them by nature of showing up to the job. Even for white collar and higher paid jobs, companies like the CYA nature of not having a contract they can be considered in breach of, but a document they can use as a stick.

US "at will" laws really are that bad. The US has a strange history with labor laws.