When I first was told about this practice of "two weeks' notice," I thought it made perfect sense, from the business point of view. As an employee, I felt like Women of Tmro podcast guest D'Shonda does! At-Will employment allows an employer, in California, to terminate you because they feel like it and without a moment's notice. Legally, you have no more obligation than they do, but this perceived two-week etiquette move is generally touted as an obligation.
If you work for a company that, as standard practice, offers a severance package to employees who are let go for anything other than "cause," i.e., being fired for doing something that needed firing, sure, you should offer them notice. This maintains the same level of courtesy and consideration the employer provides you. Otherwise, you aren't obligated to help manage a business you are leaving.
She asked the hypothetical question of why a person leaving a job was required to give the employer a heads up, but the employer doesn't extend the same courtesy. "If you were going to fire me or lay me off, you would let me know that same day," explained D'Shonda.
From there, she explained that she would give an employer the same level of respect that they gave her and detailed the lack of loyalty that organizations have for employees that they let go without warning.
D'Shonda went on to say that if companies expected two weeks' notice from outgoing employees, they should be willing to pay people they are letting go for another month. She cited "children, elderly parents or grandparents, disabilities, families, and housing insecurity as some of the reasons that firing someone without notice can be detrimental."