Yeah, I think for the most part Robotech is unavailable on streaming services.
Although Macross II and Macross Plus, both video series and compilation movies which are sequels and side-stories to the original anime which Robotech used for the Macross saga, are available, I think because they're owned by a different company (Manga I think)
There's quite a lengthy issue about the whole Macross/Robotech rights thing which might have an issue on the streaming. It's prevented the later Macross anime series from being imported (as well as a few of the movies, such as Do You Remember Love?), and there's also a side-issue with Transformers, which used the Valkyrie/Veritech mold for the Jetfire/Skyfire toy. It's very complicated.