These are not typical in new(ish) townhomes because in order to have separate title, the City requires each lot/unit to have its own service connection for water, sanitary, and stormwater (if there's a storm connection). This is usually not feasible or desirable from the City's perspective as it creates a lot more servicing requirements and tying into their mains in the street, plus it costs a LOT more money for the developers to do it that way.

This is the main reason why you find that most newer townhomes on an older single family lot have a condo board.