My company uses Upwork (as a services buyers) for hundreds of contracted hours per week, and have been for many years. We’ve never required any contractor to use screen recording for hourly work — that is optional — and have never heard of anyone using a webcam. We’ve also never disputed a single hour of work that a contractor has billed, nor have we heard any of the dozens of contractors we’ve hired mention this as an issue.

I think you might be extrapolating from a single bad data point (never a good idea, especially for a data scientist) and reaching an incorrect conclusion about the Upwork ecosystem.