Its not about how many fish are being kept. And its not a bad thing to need a fishing licnese. The money spent on fishing licenses go to local fish and wildlife agencies for the most part. With that money they are able to maintain good quality lakes and keep the right amount of fish stocked in lakes for your own convenience. If licnenses weren't necessary then there wouldn't be any public places worth fishing in the long run. This money isnt being wasted by any means. Look at it like you're paying for yourself and future generations to be able to enjoy the great outdoors, after all 20 bucks to fish all year wherever you please isnt all that bad.
On the other hand, theres many places that you have to pay to fish each and every day (pay lakes). These places really are just stealing people's money. They do need so much money to keep the lake "fishable" but not nearly as much as what they make on a year to year basis.