I've work on high performance networking file transfers. my experience is that most people who move data get very low utilization compared to the actual throughput of the network. People typically use one TCP connection, one process. high performance data transfers use thousands of TCP connections and thousands of processes.
Many other people underestimate the time/labor effort of dealing with a snowball.
I've actually only heard positive things about snowball. I would be very interested in negative feedback.
(I work for amazon)
You basically just proved my point: things aren't cheaper if you have to factor in employee cost.
But, really, I'm not trying to prove or disprove your point. Just noting that there was a situation for us where disk made sense, and we were satisfied with the outcome. Spending 4 hours of person time to save a thousand dollars was reasonable for us in a way it probably wouldn't be for many real companies, because we had comparatively little money and we're willing to work for peanuts.
(Note that I actually share your bias in this one. I both use GCP for my personal stuff and I'm writing this from a Google cafe. :-)