Why do I need a smart switch (no neutral wire required)?

Since most of the wiring of the old wall switches in traditional homes is single wire wiring. In order to save cost, the new smart switches are usually required to replace the old wall switches when upgrading to achieve intelligent transformation, instead of re-placing the neutral wire in the building. Therefore, when the new smart switch replaces the old product, only the live wire will supply power, while the outgoing wire will be connected to the neutral wire through the load. So the zero fire switch cannot be used for the product installed afterwards.