It's a common problem with many languages - I've experienced it recently myself with Rust's futures. It requires you to be explicit about spawning tasks since that requires a heap allocation and it took me a while to figure out that I had to explicitly include an async runtime (of which there are several) and start up the async tasks myself.

That said, I agree with the GP. I immediately saw that it was going to execute sequentially and thought nothing of it. Most of the time I use async/await not for concurrency but for syntax sugar and to get proper exceptions from promise based APIs instead of the GOTO FAIL control flow breaking nonsense that is catch().