Is it now a building code that all new homes and businesses have a neutral wire?
Speaking as a former electrician who has worked on everything from homes, to large commercial projects, and even to a nuclear power plant, I can tell you that you do have a neutral wire. If you didn't have a neutral wire, nothing electrical in your home would work, because you would not have a complete circuit. The author does not appear to understand what is meant when manufactures say, "You need a neutral wire." What they mean is that you need a neutral wire IN THE BOX WHERE YOU ARE GOING TO INSTALL THE SMART SWITCH.
A switch only breaks the hot wire of a circuit, so it only requires two wires: the hot wire in, and the switch leg out. Because of the way most homes are wired, MOST, but not all, switch boxes will contain a neutral wire. To find out if the location where you want to install the switch has a neutral, you'll need to remove the existing switch from the box, (you will NOT need to break any drywall). In the U.S., the neutral wire is white, but many homes use non-metallic-sheathed wiring, (commonly called by the name brand, "Romex"), so just because a wire is white doesn't guarantee it's a neutral. You'll need to use a voltage tester, and know what you're doing, to be sure you have a neutral. The good news, as I mentioned before, is that most switch boxes will contain a neutral.
Good luck!