If the solution passes some objective criteria that we have, it then forms a significant component of the on site interview where we discuss their solution in depth and have them talk about the decisions they made and opportunities for improvement. Not only does this allow us to ensure that they actually wrote the submitted solution but it gives the candidate the chance to speak from a position of authority on their own code.

But really most importantly, it is important for reviewer to be prepared for things like performance anxiety, like shy people who are not good at looking confident, to people cant think out loud (don't hold it against them if they are silent for few minutes for christ sake) and so on and so forth.

But people here throw temper tamtrum over really simple well known questions.

Maybe the companies would to the best if they made their expectations clear and realistic in ad itself. Let people know how interview looks like before hand, let them know what exactly it is you expect and then stick to it.

I have no problem working 2-3 hours on an assignment to demonstrate my knowledge. Those at least seem more realistic than some of the interview questions about the most nuanced aspects of programming.