I was trying to think of what in software is the equivilent as a 'rivet'. Something small, with a near singular purpose, one who's design has changed relatively little in decades. The only thing I could argue we have in software engineering is perhaps machine operands. For example, just about every processor will have a register and can a operand that will increment that register by one.

The result of this is that most software projects are as complex as the most advanced 'real engineered' projects. As software engineers we design whole "space shuttles" in a month. The 'buggyness' of software engineering compared to 'real engineering' is the manifestation of the complexity of what software engineering does. The tools and processes of 'real engineer' are completely ill-adapted to the rapid development of the massive levels of complexity that is software.

However, there are certain projects where a developer examines every instruction, at the detail that the 'real engineering' principles can help, however, the tools at the forefront in software engineering enable the addition of billions of washers to billions of rivets in days if not hours of design.