how is that Clearly Something Else Entirely?
I'll answer your question because it doesn't have the inane hyperbole of the previous guy.
It's different for the same reason that the guy who charges you $50 for a short flight from your local county airport to the nearest big city so you can catch an airline flight has to have a commercial pilot license while your friend who does it as a favor to you doesn't. And why the guy who is flying that commercial airline aircraft has an even higher level of certification and ongoing standards.
That reason is that there is a financial incentive to the pilot and profit involved. Lots of people here rant on a regular basis about the awful profit motives of greedy capitalists and how money is the goal, but here we're turning a blind eye to that.
The guy you pay to do your gutter inspection doesn't get paid if he doesn't do it. He gets paid more if he does ten in a day than if he does one in a day. He's got more incentive to overlook safety issues. Is the aircraft completely airworthy? Are there weather or other hazards that are being dismissed because "it will probably work out ok?"
Second, as a consumer, it is assumed that you don't know his skills or abilities and are trusting that he's got them. You know your own skills, and have a good idea of your friend's, but you have no way of judging a stranger's piloting skills until it is too late.
That's why it is established legal precedent that a commercial pilot of any aircraft has a higher level of training and certification than a recreational pilot is required to.
And why is my own use, or that other safety-minded, business-reputation-at-stake adult's use of a small quad
What makes you think the profit motive hasn't degraded the "safety-minded" nature of the guy you're paying to do the job? And "business reputation"? Just how much do you really know about the internal operation of a business? How many shoddy workmen are still in business -- and if your belief that a "business reputation" would protect you from them, how are they still in business?
a twelve year old noobie kid who says, "Sure, mister, I'll get some pictures of your rain gutters for free!
It is your decision based on your knowledge of the twelve year old kid, and YOUR RESPONSIBILITY if things go wrong. When you pay someone you 1) don't know them from Adam and 2) expect them to be the ones who take responsibility for any problems.
the guy who does it every day and cares about his reputation
If every businessman cared about "his reputation" and that "reputation" had any enforcement properties attached to it, we wouldn't need laws about commercial service providers at all, and there would be no shoddy or incompetent workmen selling services to the unsuspecting public.