And yet...I have seen people cheat on technical interviews conducted over video chat. It's pretty obvious in that situation — oh, where did that come from? — but I can see it being an issue in a highly automated interview process with minimal human oversight.
Of course, I think that the real answer for that is to use a human to interview everyone. It's crazy to treat potential future employees this way.
Had something similar while interviewing Chinese offshore developers from Accenture. We caught on that the translator was basically answering the questions, and not the candidate. As a result of that experience, I will not work with anyone that does not speak English (I don't care if it's not their first language - I can work with poor grammar & broken English and I can handle heavy accents over a phone), but I will not go through a translator (and I don't want to have to go through a translator for day-to-day work, anyway).
More than once I've conducted phone screens and heard candidates attempting to look up the answers to questions online. (Hint: it's hilariously obvious when you ask something that follows the previous answer, the connection goes silent except for a few clicks of the keyboard, and the candidate then suddenly has the answer that sounds a LOT like it came from StackOverflow.)
I've even had a candidate whisper the question to someone else in the room with them. Seriously, it's ridiculous what some have done.
We used to give people with no real experience or portfolio small homework assignments to do - one of them forwarded it to his friend, asking him to complete it for him - but accidentally CCed my boss...
While it's true that a follow-up interview would further determine a candidate proficiency, the remote interview is meant to be a weed-out test. If enough people cheat, then it becomes useless for Amazon. And yes, I've heard of people cheating on interviews, including for Amazon.
But what you can say is: "If you want me to jump through all of those hoops, send me a $99 tablet that's already configured for the test conditions you want to subject me to."
Asking questions that give an incentive to cheat are typically poor questions in my experience. Or maybe an indication that the job is gonna suck a little bit.