This statement is true in some US states (California for example) However, it is not universally true.
From the FTC rule finding (1/2023): https://www.ftc.gov/legal-library/browse/federal-register-no...
"About one in five American workers—approximately 30 million people—are bound by a non-compete clause and are thus restricted from pursuing better employment opportunities. A non-compete clause is a contractual term between an employer and a worker that blocks the worker from working for a competing employer, or starting a competing business, typically within a certain geographic area and period of time after the worker’s employment ends. Because non-compete clauses prevent workers from leaving jobs and decrease competition for workers, they lower wages for both workers who are subject to them as well as workers who are not. Non-compete clauses also prevent new businesses from forming, stifling entrepreneurship, and prevent novel innovation which would otherwise occur when workers are able to broadly share their ideas. The Federal Trade Commission proposes preventing employers from entering into non-compete clauses with workers and requiring employers to rescind existing non-compete clauses. The Commission estimates that the proposed rule would increase American workers’ earnings between $250 billion and $296 billion per year. The Commission is asking for the public’s opinion on its proposal to declare that non-compete clauses are an unfair method of competition, and on the possible alternatives to this rule that the Commission has proposed. "