…but modern phones randomize their MAC, limiting passive tracking

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The device-tracking capability is real, but its reach against modern smartphones is genuinely contested. EFF's Surveillance Self-Defense notes that on current iOS and Android the Wi-Fi MAC in probe requests is randomized by default, 'which makes this kind of tracking much more difficult,' and footfall-analytics vendors report Wi-Fi capture fell to roughly 6–12% of passers-by after Apple and Google enabled it. The limit is not absolute: Bluetooth accessories, networks a phone actually joins, and cell identifiers (IMSI/IMEI) can still expose a stable ID, and randomization is 'software based… fallible.' Present the capability and the countermeasure together. Source: EFF Surveillance Self-Defense. Date: 2026.