Things I have left in a cab
Before I turned 18, I only ever rode the BMTC. And since turning 18, I always had my trusty Chevy Beat, so I rarely needed to take cabs except when traveling in another city or during my public-transport-zindabad phase when I was using ZipGo and waxing lyrical about any and all mass transit options. That said, I did once leave my sunglasses in a ZipGo, though I managed to get them back the very next day; found them lying in the exact same spot as where I'd left them.
The other, and far more important thing I left behind in a cab was my wallet. On my very first ride in a Waymo, I was so excited about being in a driverless car that, despite the vehicle reminding me to check for my belongings, I still forgot it. I had to contact Waymo, and in an ironic twist, a human ended up coming to my rescue. My hotel was in a part of downtown Phoenix that wasn’t yet within Waymo’s service area, so a person had to hand-deliver the wallet back to me. In the end, human assistance saved the day! :)