Mandating sprinklers in apartments, but not in houses, is one of the myriad ways North America chose to make the construction of apartments uneconomical, and thus uncommon.

https://www.tandfonline.com/doi/abs/10.1080/0194436920897553...

> Veiller, concerned with strategy, proposed that legislation to prevent multifamily housing use indirect methods because "zoning legislation will no doubt be fought strenuously and perhaps defeated." He outlined an approach designed to make apartment construction, even of three-unit dwellings, prohibitively expensive:

> ‘Do everything possible in our laws to encourage the construction of private dwellings and even two-family dwellings, because the two-family house is the next least objectionable type, and penalize so far as we can in our statute, the multiple dwelling of any kind.... If we require multiple dwellings to be fireproof, and thus increase the cost of construction; if we require stairs to be fireproofed, even where there are only three families; if we require fire escapes and a host of other things, all dealing with fire protection, we are on safe grounds, because that can be justified as a legitimate exercise of the police power.... In our laws let most of the fire provisions relate solely to multiple dwellings, and allow our private houses and two-family houses to be built with no fire protection whatever’ (NHA Proceedings 1913, 212).