Software has something, which no engineering discipline has. Encapsulation. If you are building a car, a plane or a train everything affects everything.

In other engineering disciplines, a lot of work goes into preventing everything from affecting everything. You overbuild a bridge so that you don't have to consider oscillation magnitudes (other than to conservatively figure out the maximum you need to support, and that maximum will be a worst case specifically so you don't need to consider the interaction of everything else.) Any time you're adding a safety margin, you're removing from consideration all of the things that could go wrong but not wrong enough to exceed the margin.