Why Snowboarders Catch Edges
Although snowboarding and skiing are governed by the same mechanics and use the same principles for control, catching an edge is far more common when snowboarding than skiing. The main reason for this is because of how our joints are aligned. A snowboarder stands sideways to the direction of the snowboard, and can bend rather a lot in the direction across the snowboard by using their ankles, knees and hips, as shown in the animation on the right. This enables them to easily change the angle of the board without having to lean their whole body in that direction. A skier however stands in the same direction as the skis, and can bend very little in a sideways direction to the skis. This makes it hard for a skier to tilt the skis without leaning their whole body in that direction. For a snowboarder, having all this movement can be very helpful, but it can also create problems. This is because the snowboard can be put into positions that you don't want it in, which often results in catching an edge.
In the diagram you can see how a skier can only make small changes to the angle of the edges by using natural lateral movements, and they would need to lean their whole body to make any large changes in edge angles. Whereas a snowboarder can easily change the edge angle by using their hips, knees and ankles, all without leaning. A skier can make a conscious effort to roll their knees to change the edge angles, like they do to initiate a carve, but this is not a very natural movement, so is it generally not a movement that causes an edge catch.
On to the How To Avoid Catching Edges section.