How similar are Software Engineering and Engineering

The principles that apply to Engineering have been extended to Software Engineering. Is this really the right thing to do? The principles of Engineering have made Engineering products reliable, their delivery times reliable and of consistent quality. However Software products have yet to reach that level. Engineering products are made with human and machine effort, a larger part being machine effort while in software the greater effort is from the human side. Machines are predictable in nature and two identical machines will perform very similarly, while humans are very unpredictable even twins will not give the same output. The same human being's output itself is inconsistent the same task done by the same human being may give different results on two different occasions. Is it really right to apply the principles of machines to human beings or we need to create a new model?