I just talked to a friend who's a small arms engineer for the DOD.
He says we haven't seen (and almost certainly won't see) entry level tritium optics for a few reasons: First, as already stated, the licensing requirements to obtain tritium in large enough quantities to use for manufacturing sights are a significant hurdle. Second, he's fairly certain the amount of tritium needed to illuminate a sight reticle is significantly more than the amount needed for night sights. Even with significantly more tritium than night iron sights, those optics still wash out in bright light. Third, number two is why most of those optics also have fiber optic as a means of illumination: It's not a backup to the tritium, rather, it's the primary source of reticle illumination in bright light.
Also, as already stated, tritium dims over time and must be replaced every ten years or less, and at significant expense, to keep the sight functional. He expects sights like ACOGs to actually be phased out in the near future. LEDs have become so cheap, efficient, and reliable, and batteries so energy dense, that anything larger than a rifle or pistol iron sight can hold a battery with enough energy to reliably provide significant run time.
Last, adding fiber optics to a battery powered sight only adds weight, size, expense, and complexity. It almost certainly wouldn't increase the reliability.