For what the lock-in topic is concerned the expensive egress is just relevant when you want to leave your provider, not during daily operations with your consumers. Free ingress but prohibitively expensive egress is literally only there to make it as easy as possible for customers to come to the cloud provider and as hard as possible to leave. Coming to a provider or leaving them should cost the same or else it's just a trap.

This is like Comcast giving you the initial installation for free but charging you an arm, a leg, and a year of your life to allow you to leave because "the process is costly". Both practices are scummy and abusive towards the customer.