Because other engineering disciplines don't have joke applicants, because other engineering disciplines have governing bodies distributing credentials. If you're a PE, everybody knows you have a base level of competency in your field. Yeah you might not be a great engineer but you're not going to be the Civil Engineering equivalent of somebody typing questions into ChatGPT and pretending to not understand you when you ask why they're reading a script back to you.

I'm not necessarily arguing that software engineering should have some gatekeeping organization that you need to prove yourself to, but you take the good with the bad. In other engineering disciplines, a third party organization takes the responsibility of filtering out the unqualified people. In software, the hiring companies have to do it, so you end up with the first interview (at least) being spent just proving you're not lying about every single thing on your resume.