For an electronic product the ideal is to power on from a mechanical contact of some sort – for instance a button, switch, magnetic reed switch etc). That way the electronics can be completely powered down and the mechanical switch can trigger the powering up. If this isn’t possible then the design aim becomes achieving very low power consumption while off. This isn’t an issue for the microcontroller or logic IC’s typically used in a product that will control the powering up of other items, as a microcontroller can be stopped in a very low power sleep power state (a few nA of current consumption) and low power logic devices can be used with similar current consumption. However it usually is an issue for whatever component is sensing the power on.
