Gaps form where trades meet. Each sub assumes the other one has it. The general contractor finds the gap after award and someone pays for it.
Common examples are blocking in walls for wall-hung equipment, power wiring to motorized equipment, and firestopping at pipe penetrations.
Read your spec section for related work. Read the drawings for notes such as by others. State clearly in your proposal what you include and exclude.
A GC checks for gaps in a scope review before buyout. Takeoff Tool flags where the spec and the drawings disagree, such as items spec'd but not drawn.