Does anyone know if this protection was designed in from the initial conception of the major mobile OSes, or was it added on later when the relevant companies/e

Does anyone know if this protection was designed in from the initial conception of the major mobile OSes, or was it added on later when the relevant companies/engineers learned of how insecure the baseband processors are? I suppose you could explore the source of early versions of Android to see, unless it's all deep in a driver or something.