Small colonies still build under the surface first because the economics keep favoring caution over spectacle.
Subsurface work reduces visibility, moderates thermal volatility, and protects early systems during the phase when every exposed mistake is disproportionately expensive. Above-ground construction becomes attractive later, when the colony already has enough continuity in power, maintenance, and routing to survive failure without turning one broken surface layer into an existential event.
This is one reason expansion rarely looks the way distant observers imagine. The most mature colonies often begin in the least cinematic form.