While I agree with your general sentiment, note that at least in ML-class, you can resubmit quizzes as many times as you want for full credit. Thus over the course of an hour you can retake the quiz enough times to brute force a perfect score without breaking the letter (and arguably the spirit) of the honor code.

Another interesting aspect of this "online ethics" is that there's no technical measures preventing you from pulling up past quiz results, and even if there was, you could still keep previous sessions open in a browser and even if there were countermeasures against that (javascript erasing), JS could be disabled, etc.

The Programming Projects that ML class had were slightly better metric of performance as there's more work that would have to be plagiarized, and if you're just going to go through life outsourcing all of your work then I guess that's your prerogative. However, I think that if you wanted to be very serious about actually testing for knowledge of material then the addition of some sort of interview component (phone/skype session), while time-consuming, could help.