Modular construction has a number of advantages, not the least of which is cost. The actual construction is typically done in non-union shops in neighboring states and the resulting modules are trucked to their final resting place. Modular fabricators also tout their product as benefitting from a superior level of quality control and precision.
Lower-intensity variations on modular construction, typically referred to as “panelized” construction have been around for decades and are common in new home construction in the suburbs. The photo below is my son Jordan standing next to the second-floor of his home shortly after it was delivered 4 years ago.