As the saying goes, California is the United States... just 30 years in the future.
(Note that often this is a good pattern, but not always!)
(Note that often this is a good pattern, but not always!)
But the relevant point here is that California has long had state law banning most forms of non-compete clauses in employment contracts. It's considered to be one of the strengths of Silicon Valley and other California industries -- talent can move from established company to established company, or established company to startup.