Somehow this reminds me of one I missed: all the simulation-based driving improvements at Waymo, Cruise and others. Hard to know if it's strictly RL or not from "we train neural networks while driving in simulation" but it's similar enough for my taste.

I'll be curious to see the set of domains where a hybrid approach (some real world, lots of simulation) works out. The nice thing about simulation is that you can experience lots of things that you never want happening in the real world (e.g., child runs in front of car with only X00 ms to impact). Trading off the difficulty of accurate simulation versus needing to trust that the model will behave correctly under a situation you could have simulated, will (likely) be an interesting liability challenge for autonomous driving at the least.