I think it's important to note a few things as we all grapple with this. I certainly don't have the answers. The first is that any remote test taking is going to be controversial. Putting a lockdown browser on your computer? Data privacy. Doing room scans? Physical privacy. Not doing any of those things? Test integrity. There's risk involved with everything. I mean, the whole point of these exercises is to keep an eye on test takers for the purpose of test integrity after all. Nothing's going to be perfect.
The other thought that comes to mind is the additional amount of data held by an entity, in this case, Instructure. If they were to implement a program that stored room scans or installed applications on people's personal devices (like some sort of lockdown browser), that would add to the already substantial amount of data they manage. This is a risk management concern.
Just my opinions, not speaking officially for anyone, but I, too, have thought a lot about this. I don't think anyone really knows what the future looks like for remote proctoring in the long or even medium term.
Take care!
Nathan