That's why understanding your client in your first few meetings before you commit to the project is SO important. I let go of a lot of deals in my career because the client was very stingy - they want to know how you spent every second of your time or they want to know how many vacations you take, etc. It boils down to trust.
It's your responsibility to instil trust and this trust will pay itself off in the long run.
Also, I work with Google cloud, I'm always the project owner and at no point my client has access to the source code until full payment for the project has been made. So, it also depends how desperately they want that software/product.
They stopped paying? Simple. Just add an auth layer to the app (very simple to do with Google Cloud). They will come to you if they really need that product that bad. They didn't get back to you? Too bad, in my contract, it says this is now your IP and you can do whatever with it, including selling it off to a competitor or someone else who can find use for this.
The point is, I don't see why your personal space needs to be violated by an intermediary agent for you to be guaranteed to be paid..
But, if like many people you are getting burned by non-payment, then turning this feature on seems like a pretty good route to go for stability in your wallet.
Why would giving these people more power over you result in more payment ? They are looking to exploit these freelancers, and this gives them more power.
Why would any reasonable person expect that giving cheaters more power over you result in less cheating ? It will obviously increase the chance that you, as a freelancer, won't get paid.
https://hackernoon.com/why-you-should-never-use-upwork-ever-...
https://www.trustpilot.com/review/www.elance.com
https://entrepreneurs.maqtoob.com/a-top-rated-freelancers-ad...
https://screenshotmonitor.com/blog/how-to-avoid-scams-on-upw...
I'm not saying you're wrong, but you made a pretty contentious statement and your evidence is lacking. Do you have a more explicit link to what you're talking about?
You don't need a big brother watching your every working hour. There's happy mediums, this Upwork spy thing certainly isn't it.
"I've never had a client expect to be able to look over my shoulder"
Right well UpWork isn't your client. I don't think your clients should, and to another person's point, yes your clients should trust you.
But this is in the case of when you do the work and the client _doesn't_ pay. This is UpWork covering your ass, when they really have no obligation to. They want a way to prove that you are least did some work, so likely they can go after the client later and recover costs.
This seems absolutely reasonable and honestly a heck of a bargain. Again, I think the implementation of counting keystrokes seems like a stupid way to do it, but coming up with a tracking method to _optionally_ guarantee payment even in the case of client non-payment is the deal of the century in the freelance world. Don't believe me? Try freelancing for a while and see how many clients stiff you after you've completed the job. There are literally advertisements in the NYC subway about it.
(Yes, retainers, payment up front, et ceteta -- no the world does not always work that way.)