SUA missing from "windows features"

The official instructions for installing the windows Subsystem for Unix-based Applications list two steps:

1. Open the "Turn Windows features on or off" window and turn on "Subsystem for Unix-based Applications."

2. Download and install the USA Utilities and SDK.

I'm stuck on step 1. The windows features dialog box on my Windows 7 Pro x64 system doesn't list SUA at all! None of the official or third-party instructions I've found address this possibility.

Here's a screenshot showing on the left, an image from the installation tutorial video, and on the right, my own system. Notice no "subsystem" on the right.

If all else fails I could use Cygwin, but I wanted to try out this alternative.

This is only supported in Ultimate. Sorry!

More specifically, Utilities and SDK for Subsystem for UNIX-based Applications in Microsoft Windows 7 and Windows Server 2008 R2

Lists the following as system requirements: Windows 7 Enterprise, Windows 7 Ultimate, Windows 7 Ultimate 64-bit, Windows Server 2008 R2

Which is sad, as Professional could benefit from NFS server ('mount' is not recognized as an internal or external command, operable program or batch file.)