I have this similar gripe when it comes to http proxy configuration. It's invisible to you until you are in an execution environment where you are mandated to use the providers proxy configuration.

Some software reads "expected" env variables for it, some has its own config or cli flags, most just doesn't even bother/care about supporting it.

Chiefly because "supporting it" requires a full JavaScript interpreter, and subscribing to changes in "system settings" during the lifetime of your program. Easier just to support http_proxy/https_proxy/no_proxy (and what standard for no_proxy? Does it support CIDR ranges?) or even less flexibility than that.