Why does the Go team refuse to fix this? Golang is supposed to support Windows. Forcing Windows users to adopt non-windows conventions is not what "support" means. We can't build a product with Go and then tell our customers' IT teams "You need to change the way that you reference environment vars because the Golang team refuses to recognize "%PROGRAMFILES%" as an environment variable even when running on Windows".

To revisit some points raised before:

"according to docs, os.ExpandEnv will only expand $name and ${name}". Nice to know but does not address the problem. golang could always provide another alternative such as @jeffreydwalter's suggestion to provide e.g. ExpandWinEnv.

"there are alternatives like golang.org/x/sys/windows/registry.ExpandString". Unless something has changed, registry.ExpandString doesn't work for this purpose (see #24848)

"there's an easier workaround here - simply replacing %FOO% with ${FOO}". It is a difficult proposition for anyone developing with Go to tell their corporate clients that they need to remember that just for their product, they need to change the way that they reference environment variables in strings.