This isn't remotely true.
The bandwidth alliance exists, and a lot of cloud companies are on the list: https://www.cloudflare.com/en-gb/bandwidth-alliance/
The actual answer is much more complicated. For example, Google Cloud offers two different bandwidth tiers: premium and standard. The calculation on the OP assumes premium since that's the default option, but obviously it's much more expensive.
Google cloud's "premium" bandwidth is much akin to AWS Global Accelerator since it utilizes Google's own backbone network for as long as possible before exiting at the nearest peering point between Google and whatever ISP your end user is at. AWS Global Accelerator has some other options available, that make it fundamentally a different product, but the routing characteristics are much more similar to GCP Premium bandwidth than anything else AWS offers.