Your printer's design assumes that you leave it plugged in for an extended period of time - for example, you turn it on when you start work in the morning and turn it off when you finish work in the evening.
Due to the energy-saving design of the circuits, the printer requires some time before it turns on automatically after you plug the printer in again soon after unplugging it.
The length of time required for your printer to turn on automatically soon after being unplugged depends on your printer's model and the voltage - refer to the table below for this information.