First, here's a general point: many of the auto OEMs describe their adaptive cruise control function ("ACC", called "Traffic Aware Cruise Control" or "TACC" by Tesla) separately from their forward collision warning ("FCW") and automatic emergency braking ("AEB") functions. It seems like splitting hairs, but it is FCW and AEB that respond to stopped vehicles, by design. The reason for the cautions that ACC will not is probably for cases in which FCW &/or AEB can be disabled by the driver, but who might engage ACC anyway. In that case, the caution that ACC does not respond to stopped vehicles is necessary to keep drivers from thinking that it does by itself (i.e., rather than FCW & AEB even when ACC is active).
Second, here's a specific point: assuming the Tesla vehicle that struck the fire truck had at least software 8.0, then it was handling stopped vehicles differently than any of the examples of crashes into stopped vehicles or stationary obstructions by Teslas with pre-8.0 software, either before September 2016 or by vehicles after that that did not upgrade to software 8.0 or later versions. As Tesla explained here
Upgrading Autopilot: Seeing the World in Radar , "fleet learning for radar" software changes were made to better handle stopped vehicles and stationary obstructions.
Third, here's a reminder: Tesla's FCW & AEB are safety features standard in vehicles starting with those having radar, but Autopilot (which is Autosteer for steering with TACC for maintaining space behind a vehicle being followed) is a paid upgrade. Each of those named features is responsible for different tasks, but very often "Autopilot" is used by the press and consumers to refer to any of them. This by itself can lead to much confusion when people debate what a Tesla vehicle should, could, or did do. Referring to "Tesla technology" in a particular vehicle with identified hardware version (1, 2, or 2.5), software version, and purchased options would avoid much confusion. Unfortunately, for people not willing to understand those distinctions, "Autopilot" will no doubt continue to be the catch-all name for any and all driving-assistance/autonomous-driving technology in any Tesla vehicle. It's a failure to take Einstein's advice: "Everything should be made as simple as possible, but not simpler."
