One factor may be that mechanical engineering remains dominated by expensive proprietary software, and the field is largely OK with that. Programming is unique in the sense that programmers can create their own tools, and have adopted an expectation that the most advanced tools should be free and easy to obtain. This culture could easily extend to making the training materials free too.
Another factor is that "coding" is the hot field right now.
The lack of formal professional organizations is the biggest boon for computing. I'm glad we don't have an artificially low supply of programmers like we do doctors
That isn't a factor of the artificial scarcity however, that's a factor of the teaching standards.
In Australia we have a very limited number of surgical training positions each year. We could do plenty more, but we don't... more or less because surgeons are snobs who want people to go through the same hoops they went through.
I think the two approaches are not that far apart. High teaching standards require an elite and dedicated student body and will weed out all that don't conform. An aggressive entry barrier for a limited number of seats will push applicants to compete with each other and select for largely the same thing, only earlier and at a lower cost for the students and the educational system.
I've experienced both systems "easy to enter, next to impossible to finish" vs "highly selective, smooth sailing after that", I can't say there is a definitive superior solution.
Having seen the absolute dire code some programmers put out (some being very well paid for it too); I'm very glad there are far fewer doctors like that and those that turn that way lose their accreditation and get shamed out of the field.
Another factor might be that the term engineer is a protected term, and not unlike doctors and lawyers there exist state-regulated tests to confer such a title.
I'm sure that a mechanical engineering course would be possible, but the course would have to clearly state that it cannot accredit the credentials to actually work in the field.
Seems obvious that a non ABET school would never give engineering credentials, yet community colleges still offer technical courses on mechanical and electrical engineering and even associate degrees in those fields. Professional engineering requires ABET bachelor's and passing EIT and then the PE exam plus 4 years professional experience.
I have a degree in Mechanical Engineering; I have not taken any professional licensing exams. There's an overwhelming majority of jobs that I could take in the Mech E field right now, without a need for the PE license.
I'm not sure the precise details, but there's an "industrial exemption" for engineers who work for a company that makes a product. Most of the MechE's in my department do not have licenses. One colleague is pursuing hers, but mainly on the grounds of "just because I can, so why not."
I got as far as an EIT but then went back to school and changed careers.
Engineers mostly need a PE licensure if they're going to be signing off on drawings and the like for regulators. Thus PEs are pretty common in civil engineering and, I assume, structural engineering in general. But most Mech Es aren't licensed in the US even if they have degrees from accredited schools.
Another factor is that "coding" is the hot field right now.