That's only true to a point. In addition to the consumer-directed packets, large volumes of traffic for Google and Amazon never leave their networks. Shuttling data between datacenters for Google; moving data within the many cloud services of Amazon; or transferring between the two companies (e.g. GCS to S3). This means it's no longer a given that telcos must be larger.

The closer we get to living "in the cloud", the more our traffic can be seen as a window into operations taking place within and between cloud services.