Complex sentence: The efficiency is obtained by the nature of the MVNO business model in that an MVNO incurs no significant capital expenditure on spectrum and infrastructure that an MNO does and does not have the time-consuming task of rolling out extensive radio infrastructure.
Split into simpler sentences: The efficiency is obtained by the nature of the MVNO business model. An MVNO incurs no significant capital expenditure on spectrum and infrastructure and does not have the time-consuming task of building out extensive radio infrastructure.