If you look closely when walking around a neighborhood of row houses you'll find that they don't actually share side walls. Each row house has its own exterior walls with siding / exterior finish that may end up directly adjacent to the next house's exterior wall. This is apparent in areas where one row house has been torn down or is larger than its neighbor. Of course sound and fire might travel through these more easily but they share no structural elements.

For an example of what I mean, take a look at SF's Outer Sunset district on street view.

Edit: it's possible that terminology and construction methods vary a bit between cities so all I can say is that you can certainly build a row of houses that share no structural elements.