On Mars
Do I need a tech tile to build a single building that is not part of a complex?
The rulebook's Colony Main Actions section says a building exactly 2 hexes away needs no Tech; the designer rejected claims that a lone building blocks LSS progress.
No. Tech is only required to create or extend a complex. A lone building two hexes away is built at normal cost; it gives no progress cube, but the LSS marker still moves and the LSS reward is still available if the colony needs that type.