simply presses a green button once and the rest of the start procedure is automated.

A typical starter includes protection against overload, both electrical and mechanical, and protection against 'random' starting - if, for instance, the power has been off and has just come back on. An acronym for this type of protection is TONVR - Thermal Overload, No Volt Release. It insists that the green button is pressed to start the motor. The green button switches on a solenoid which closes a contactor (i.e. switch) to primarily power the motor.