FWIW, in the Netherlands many collective bargaining agreements DO stipulate a minimum notice for firings (barring special circumstances like gross neglect, committing felonies, etc.). For example, my first system admin job had a contract mandating 1 month's notice in both directions. Usually the notice given by the employer is longer than the notice given by the employee and the notice duration for the employer increases with seniority (so after several years I'd be owed 2 or 3 months notice).

I think the main reason there's no notice by employers in the US is the lack of unions/organised labour to fight for rights like these.