Problem is, people take logo design - and a lot of other design - at face value.
A lot of people assume that logo design merely means opening Photoshop and throwing some text and other elements together. And for some designers, that is true.
But for any professional designer, he or she would research the target demographic, take the business' culture/products/mission into account, and incorporate it into something that reflects all of that and is versatile, meaning it can be used in flyers, a web page, T-shirts, or even a billboard.
And a lot of times, you don't get just one logo. Often you will need a full logo, an icon, and a simplified version of both (if they are complex and not print-ready).
So that's what a business is paying for, not just a bunch of stuff thrown together in a logo. And given the value of the work, it's worth much more than $5 or $50.