>Or what about other engineering disciplines? Does one really ask a Mechanical Engineer or a Civil Engineer about their side projects?
Not civil engineers (because it's hard to build a 4-lane suspension bridge on a Saturday) but very often candidates in electronic and electrical engineering have side projects that can help them land a job. Are the electronics breadboard projects that you did in your garage absolutely required to get a job?!? No, but they help you stand out among the crowd.
The reason that <computer programmer> is different from your analogies of marketers, lawyers, recruiters, etc is that the activity of programming is often a source of fun and play. Some children with curiosity start programming on their own and continue it into adulthood. (And hence, they might have some personal github projects.) In contrast, people typically do not do "lawyering" for recreational fun.
Programming is enjoyable enough for some that side projects on github are mostly a voluntary and organic phenomenon. Some employers are taking advantage of that signal and prefer to hire those types of programmers.
Not civil engineers (because it's hard to build a 4-lane suspension bridge on a Saturday) but very often candidates in electronic and electrical engineering have side projects that can help them land a job. Are the electronics breadboard projects that you did in your garage absolutely required to get a job?!? No, but they help you stand out among the crowd.
The reason that <computer programmer> is different from your analogies of marketers, lawyers, recruiters, etc is that the activity of programming is often a source of fun and play. Some children with curiosity start programming on their own and continue it into adulthood. (And hence, they might have some personal github projects.) In contrast, people typically do not do "lawyering" for recreational fun.
Programming is enjoyable enough for some that side projects on github are mostly a voluntary and organic phenomenon. Some employers are taking advantage of that signal and prefer to hire those types of programmers.