That's because -- and this is the real problem -- finding the flaw in a specific methodology is a lot of work. It's often not just one thing that throws the numbers off by 200%, it's one thing that throws them off by 12%, then another by 7%, and twenty other little things that add and multiply up to an inaccurate overall conclusion. It can take multiple hours to figure out what actually happened and people don't have that kind of time, so the majority of people only have time to read the conclusion and who sponsored it.
In theory the solution to the problem of everyone having to personally evaluate every study is for a trustworthy reporter to do it for you, but that hasn't worked ever since reporters figured out that "Uber eats souls" gets more clicks than "wage study methodology miscalculates wages."
But if you want a real flaw in this study, how about this one -- most other jobs don't let you count transportation expenses against the hourly wage. Obviously an Uber driver's transportation expenses will be higher, but that doesn't mean you can discount them in the other cases when you count them in this case.
If someone has a 30 mile commute (because living closer to work is even more expensive) at $0.53/mile, that's 60 miles a day, so $31.80 in daily incremental expenses to take the job. 8 hours at federal minimum wage ($7.25/hr) is $58, so after transportation expenses their hourly wage is $3.28/hour. For someone with a 50 mile commute it's $0.63/hour. Suddenly Uber doesn't look so bad.