I immediately noticed this as well. This API has flags for "asynchronous" requests, but Go style is to provide a blocking API, and let the caller decide to use a goroutine if they need concurrency.
You get a channel - you can read from it until it's closed which is always safe. Go-routines are cheap so you don't care about the background details. For simplifying HTTP, this is great.
I got a lot of feedback that I shouldn't do that, so I moved the asynchronous requests to specific functions e.g GetAsync and made the standard API synchronous.