And the public as well. If I hire a lawyer, I have a signal that they probably have (at least) a rudimentary understanding of law, and are licensed to practice law. If I see a medical doctor, I know they have a degree and are licensed to practice medicine. If these people wind up negligent or put people in harm, I know that they have the chance of losing their license to practice law or medicine.

If I need an engineer, I should have at least some assurance that they know what they are doing, and that they aren't going to act unethically or against my best interest. I should also have some assurance that the fact they hold a license, means that they (probably) haven't been negligent, or harmful with their practice.

This is what Texas used for its software licensure examination: https://nceesorg.wpenginepowered.com/wp-content/uploads/2015...

All of that seems like, the barest minimum that I don't think anyone would disagree with to call someone a software engineer.

I mean, isn't that the point so as to avoid devaluation of the trade and thus increase potential earnings?

I think this simplifies the problem of people self proclaiming to be "engineers" without any kind of qualification, metric, or known meaning.