This is all very reasonable, and I agree that it would be nice if Lyft and Uber made adjustments to upfront fares, which would benefit the driver, just like it would be nice if all passengers were required to give tips. That being said, what you are suggesting here draws a very thin line between being an independent contractor and being an employee.
Above and beyond that, I don't think the driver in this case was born yesterday. I think that the driver in question is probably very familiar with local traffic in the area, which can get quite slow, and come to a crawl at times.
Let's face it, when it comes to estimating drive times, it's a lot easier to get the estimate right when you are dealing with traffic in Nebraska, vs traffic in Los Angeles.
One day, I drove from San Diego to Los Angeles on a SATURDAY afternoon to meet this girl I met online. On the way there, I ran into THREE traffic jams! Took me way longer than I thought it would!
The driver knew how much they were going to get paid upfront. The driver knew how many miles they were going to go, and based on the time of day and driving experience, probably knew roughly how accurate the time estimate might be, and that sometimes, the time estimate is off, especially in Los Angeles traffic, where it's not always possible to quote accurate drive times, especially during certain times of the day.
Life isn't always fair. Sometimes, when this type of stuff happens, you kind of have to just roll with the punches, and be happy with the good that comes out of a specific situation. Or you can complain about it, look only at the negative side of the issue, and be mad and complain that you lost half an hour of your life that you can't get back. Meanwhile, the guy working at the taco truck is thankful for his $10 an hour...making what you made in an hour in a full day of work.