Yes and no. In theory, they don't need a reason. In practice, they're concerned about lawsuits, politics, and unemployment insurance.
First of all, if you sue (and you can for a number of reasons), that means litigation, even if frivolous. Secondly, most orgs don't like giving person(s) the power to fire for no reason (politics / abuse potential). Finally, unemployment insurance is a big cost; if you get "fired for cause" their rates don't go up (this systems a joke, but that's a story for another day)
So, contrary to what you might think, and people will claim on the internet, it can practically be quite hard to fire someone. You just can't sue because you got fired fired for no reason, just for other stuff (eg. discrimination)
First of all, if you sue (and you can for a number of reasons), that means litigation, even if frivolous. Secondly, most orgs don't like giving person(s) the power to fire for no reason (politics / abuse potential). Finally, unemployment insurance is a big cost; if you get "fired for cause" their rates don't go up (this systems a joke, but that's a story for another day)
So, contrary to what you might think, and people will claim on the internet, it can practically be quite hard to fire someone. You just can't sue because you got fired fired for no reason, just for other stuff (eg. discrimination)