Probably the HDMI only appears as a choice if something is connected to it. What does the user manual of your TV say about it?
A Roku or a comparable device will offer you Netflix and much more. Start your exploring at http://www.cnet.com/news/chromecast-vs-apple-tv-vs-roku-3-which-media-streamer-should-you-buy/
Is there any hope for people who have older TV's which have the HDMI in the back, but no HDMI channel? Is there a router or some other device that can give them access to Netflix etc....? Is there some secret to finding the HDMI channel if it is not listed on screen?