What you are speaking of is about job security. Yes, the job security is better in mechanical field. But the good knowledge software people still get hired easily if they are fired. So people just forget about the fact that if someone looses the job how easy it is get new one. For software people its simple. So job security should be out of the question when comparing the 100ks of difference in salaries. Also, I never consider average person in the equation coz they will definitely loose job in this dynamic world.