You'll need to check each switch location for a neutral wire. It is common even in homes with neutral wiring, that not all switch locations have a neutral wire.
For maximum flexibility, especially if planning to add a lot of smart dimmers, you really should take a look at the Lutron RA2 Select product line. The new PRO+ dimmers work with or without a neutral wire, can drive all kinds of lighting loads including more specialized fixtures, and the selection of color schemes will please the most demanding spouse or Interior designer.
It's more expensive than Caseta, but uses the same app based software and integrations with HomeKit and other systems. It does "require" purchase through an electrician or dealer, but is widely sold bu electrical distributors or online sources to "anyone".
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.
You should pull this article and re-write it. It's really poorly researched. You don't explain what a neutral actually is despite the title, why the code was changed to include a neutral in every switch box, no mention of local building codes and how that affects when it was required in your area, etc. I'm also an electrician and was mildly interested in an in depth discussion of the neutral wire and was sincerely disappointed about the article.
Plus the photo at the top is of an exposed outlet, not a switch. All outlets have a neutral wire, before and after the 80's, or they wouldn't work. Really lazy writing.
I am a homeowner and a licensed & insured electrician. I firmly believe in DIY work in your home whenever & wherever possible within reason. However, electrical work is not one of those places for most people. If u need to ask the question “does my house have a neutral”, than u have no business near any of ur homes wiring. This shows u dont even have the most basic understanding of the fundamentals of how a simple circuit works, let alone ones as complex as the ones in ur home. U will most likely end up creating a dangerous situation for urself and for ur family. PLEASE do all the other DIYers who may be “guided” by this article a favor, and remove it until it is properly researched.