This could be something worth fully automating -- they have a limited number of options on the menu, and a less-limited but still defined number of permutations on those options. That problem space may be small enough for converting text-to-speech. The downside is that you'd still have to have someone on-call to try to rework any order statements the system has a low reliability score on.

I don't understand why they don't have an app yet for ordering (at the drive-in and maybe delivery too).

The combination of app-based ordering and drive-through delivery is one I strongly believe to be underutilized.