A good article. Surprisingly, reaching the sun is actually quite difficult. Earth travels around the sun at around 67,000 miles per hour, which keeps it in a roughly circular orbit at 1A.U. This means any trash we launch into space is also going at roughly that speed.

In order for trash to reach the sun, you really need to slow it down significantly so that the sun's gravity can pull it down closer, but 67,000 mph is incredibly fast. We just can't build a rocket big enough to carry enough fuel to make that sort of deceleration feasible on a large scale.

The missions we have sent to the sun and Mercury are necessarily small craft, and most of the decelerating is done through several gravity assists from other planets, which means complicated trajectories and more chance of things going wrong. Not how we want to be handling our trash!