His argument was that you can reasonably expect people to know how to handle such technologies safely, not that he expects people to know how to build a WiFi Router from electronic parts themselves.

Using your analogy it would be sufficient for a person to know how to handle electricity coming from your wall or the plumbing under your house safely. And generally people do know how to do that.

Everyone who is regularly using WiFi networks knows that he/she can see the names of other WiFi networks in their vicinity. Therefore people using WiFi generally do know that this information is publicly broadcasted and available to be collected by anyone interested in doing so.

No one believes that he is the only person being able to somehow magically see the name of his neighbours WiFi.