You're right, and... I'm working professionally using DL for computer vision, for robotics. We spend the majority of our time writing the business logic around the learned parts. To get all of that code bug free and fast is way harder in python that I expect it would be in Rust. Rust's ndarray ecosystem is immature, but Python's static type checking ecosystem is too (no stable mypy stubs for numpy ndarrays), as is Julia's AOT compilation story.