Many professions have legally protected titles. In the USA it's illegal for someone without a CPA license to claim the title of "certified public accountant", and since engineering failures can have fatal consequences the same protection is offered to the title "engineer" (or "professional engineer", etc) in some countries.
You might argue that it's the certification that matters, not the title, but the title of "structural engineer" has been around for approximately as long as humans have been stacking up rocks to sleep under; the certifications have not.
You might argue that it's the certification that matters, not the title, but the title of "structural engineer" has been around for approximately as long as humans have been stacking up rocks to sleep under; the certifications have not.