alt Hacker NewsDrilling a few holes to mount a TV is so straightforward that nearly everyone can do it, in contrast to patching drywall, so excluding the cost of hiring a professional for that case is reasonable. Granted, you might be able to learn how to do it with some youtube videos, trips to home depot, and trial/error, but the cost of that will quickly exceed the cost of a handyman if you value your time at all.
Patching drywall is also so straightforward that nearly everyone can do it, unless it's a very large hole. It's a one trip to Home Depot or Lowes job.