mcelroytutoring
Thanks for posting. This is an interesting article, even though it is rambling in sections.
The article seems to be pointing to problems with the ProctorU system. Primarily, the issues boil down to ProctorU having limited access to testtaker's computer and its running processes, since ProctorU seems to be only using a browser extension. This isn't surprising and this problem has been known. What is somewhat confounding is that agencies using ProctorU's services do not seem to have implemented new standards to prevent cheating.
GMAT On-Vue system appears to use different arrangements. It seems to take complete complete control of the testtaker's computer and hence has access to everything that could be happening. So the problems here could be fewer or non-existent.
I think that testing agencies have a powerful weapon. If testtakers are discovered to have cheated, then they can be banned, reported to programs and even legal actions taken against them. It is possible that these agencies are relying on these mechanisms to deter cheating. Time will tell how this all pans out.