Another huge reason is HR salary restrictions. In large companies, a senior individual contributor cannot make more than X, while the going market rate for peop

Another huge reason is HR salary restrictions. In large companies, a senior individual contributor cannot make more than X, while the going market rate for people in hot specialities of the day is often higher than that. Contracts are a way to circumvent the HR restrictions. Many contractors are staying for a couple years within the same company and are essentially an employee in everything but a name.