"Software engineer" is a common title - I'm UK based, not even US - and that perhaps helps to differentiate practical development work from more academic computer science work: the two activities truly are quite different. "Engineers" is probably just an evolved shortening of that "Software Engineer" title.

I know what you mean though: Chartered Engineer is a proper thing for example, with exams and governing bodies involved, and anyone in construction who just decided to call themselves a Civil Engineer would likely get into some bother for doing so.