Newton's Laws fit into three lines because most of us are already familiar with the integral concepts: force, mass, inertial reference frames, etc. The concepts involved in quantum mechanics are fairly alien to most people, so explaining the theory takes longer. The fundamentals of orthodox QM can be fit into three principles: 1) The Time-Dependent Schrödinger Equation; 2) The Time-Independent Schrödinger Equation; and 3) The Born Rule. Even writing these out in full doesn't take long. Explaining what they mean, however, can take a while.

Frames of reference are fairly obvious in SR. In General Relativity they're more non-trivial.