Glad I'm not the only one frustrated by this. In all my previous cars they chirp the horn when they auto-lock as you walk away... which is reassuring. With my "new to me" 2018 March MS P100D, this option is not available so I have to look back to make sure the handle and side mirrors have retracted. As confirmed by the OP, the option IS in the Service Menu.
But additionally it's also in the Tesla Tutorial videos!! Go to Theater > Tesla Tutorials > Watch the first video about the Owner's Manual and notice the video is for legacy vehicles and shows the portrait display. Pause after 17s and you will see on the screen the option "Lock Confirmation Sound".
I also had a Tesla mobile service for a different issue but while the technician was there I asked about the missing lock confirmation sound option. He was surprised it was not there and promptly showed it to me in his 2016 MX!!
So it is there in the video, there in older cars, there in the Service menu... but missing from the main UI of my 2018 MS. Why??
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