Those are not the ones figuring out what materials need to be used, what dimensions everything needs to be, how things should be fastened, what environmental factor need to be considered, what natural stresses everything needs to be built to withstand and so on. Those are just the workers, important for sure, but not the ones doing the engineering.
Mechanical engineers and civil engineers design our infrastructure. Architects design buildings. They're not scientists. There are computer scientists and computer engineers. The scientists figure out zip compression algorithms. The engineers make the programs that zip and unzip files.
