Right, if Google doesn't think you are in the US, you won't be able to download Voice from Play. Which is really annoying if you actually are in the US...
That has always been the case, but is not so today.
Google Play knows where I am as it offered the Nexus5 in Japanese Yen. Nevertheless I successsfully installed Google Voice just now.
Can you set it up? I've always been able to install the APK, but if you don't already have a GV number, it wants to send an SMS to a real phone number as part of the setup, and that number needed to be American.
As you say, cannot set it up. I guess nothing has changed.