My interest in oddball cards dates back to my childhood, when I would often accompany my mother during her grocery shopping and would pick out some of my staples based upon whether or not a product included baseball (or football) cards in the box. I was fortunate in that my parents, though not wealthy, made enough money that we were able to buy the name-brand cereals (Kellogg's), snacks (Hostess) and bread (Wonder Bread-for football). Contrast this situation with the one that many families faced during the mid-late '70s fiscal crisis, where they were trying to maximize their dollar and avoided the name-brands for the generic ones.
As far as this particular card set (2002 Seattle Mariners Knothole Gang)- I can't find much information on its distribution. I recently bought the entire set, which includes this 2nd year Ichiro.
The term 'knothole gang' has its origins in the early part of the 20th century, but the practice dates earlier, when ballparks were being built with wooden fences. Children who weren't able to afford the price of a ticket would gather around the areas where the knotholes were, giving them a view to the game. Over time, teams (as well as individuals & businesses) began offering tickets to children in the community who otherwise might not be able to attend a professional baseball game. Some of these were offered through incentive programs (good grades, get into a game) at local schools, or given away to kids for good behavior. One individual, former Mariners manager and then later bench coach Rene Lachemann, started Lach's Kids, a program to help low-income children and urban youth groups attend major league games. You can read about his story here.