There is a numbing repetition of MacKay's themes throughout the literature on wearables. Just as he insisted that telemetric devices must operate "outside the awareness" of "unrestrained animals," today's developers stress that wearables must be "unobtrusive" to avoid raising alarm. They are to be "continuous," "pervasive," and, crucially, "low cost" in order to achieve economies of scope. The digital marketing firm Ovum forecasts 650 million wearables by 2020, nearly double the number used in 2016, and its research suggests that growth is largely driven by the lure of surveillance revenues.

Shoshana Zuboff, The Age of Surveillance Cap…, loc. 770