Indeed. I'd also add "Getting somewhere cheap..." as a primary incentive for these rides.
I've used Craigslist "ride shares" between Montreal<>Toronto ($30) on a number of occasions. I fully understood the risks I was taking compared to paying 3x as much for a safer train ride ($100).
The vehicle is advertised as being a Mercedes mini-bus [1] with seating for ~8 people but usually only has 6 passengers and plenty of extra space. The driver was usually an immigrant from China who drove the route everyday, so they know the route well and are always very efficient and reliable. Their lack of english-speaking skills was somewhat of a concern but never caused any issues in practice.
I was more concerned about how they managed to survive on what was basically a minimum-wage payout for a full-day of driving. But there is clearly a supply of workers. Plus they made extra money doing deliveries of newspapers between cities.
Paying for an over-packed Megabus for a comparable $30 price was out of the question because it's always full, always noisy, full of extra stops in between, smells halfway through if you're near the back, etc, etc.
Consumers are capable of making economic cost comparisons. You go on Craigslist searching for bottom-of-the-market rides to save money, there's always a certain expectation of added risk. Same goes with Megabus, almost all of the worst bus drivers I've seen are employed by them, but being outside of the 'sharing' economy seems to protect them from similar scrutiny.
When I say "no maintenance", I don't mean ripped carpets and dirty windows. We're talking no functioning brakes.
When there's an accident, the bus driver just runs off.
Could you elaborate?