There was an option to post "manual" time without screenshots; I have used it a few times, but mostly I was sitting before the computer anyway. I doubt most of my customers actually looked at the screenshots; I remember one distinct case when a customer actually did, read my todo list for the project and provided feedback and answered questions without me even asking :) It was when we've just started working though, so naturally he was cautious.

Also, I my case it was a requirement from the site (Upwork); in return they guaranteed the payment, that is, if I provide screenshots, I get paid by Upwork even if the customer doesn't pay. When I started a few years ago it was very reassuring, although I don't think this actually happened with my customers.