See previous discussion [1]. What's interesting about this case is that the customer was able to prove what happened, and Lyft still refused to fully engage until the press was involved, and even then, refused to answer direct questions about how it investigates fraud cases and what penalties will be assessed against drivers who do this.
My own suggestion of a solution (in the short-term) remains to alert passengers that they are getting charged a fee for making a mess in the car before the trip concludes, within the app. It's possible this could lead to confrontation between drivers and passengers, but taxi cabs do this every single day. Moreover, I have to think very few Uber/Lyft drivers would be brazen enough to assess a charge when no damage had been done. At the very least, it would allow a passenger the opportunity to take their own photo and video before exiting the car.