The software engineering profession is moving at light speed compared to any of those other careers. It is specific to us and not engineering as a whole too - as you point out, structural engineering does have qualifications required (chartered status).

Medicine does move on, but a lot of what a doctor needs to do doesn't. And the bits that do are actually a problem with there not being a good way of ensuring that doctors use up to date techniques.

The difference is that structural engineers and doctors are safeguarding safety, and (most) software engineers aren't. If someone suggested people should need chartered status to work on medical device software I don't think that would be as controversial, and will get progressively less so as the discipline is less brand new and progress slows down a bit.