It makes sense to license electricians, crane operators, doctors, lawyers, and many other professions who do safety-critical work.
Only a very small minority of programmers work on software that could actually hurt someone (at Boeing, Toyota, etc...).
There's no reason to create a legal barrier to entry for programming.
Similarly, there would never be a general licence for "programmer". But some day there probably will be (and indeed probably should be) specific licences for things like "have back-end access to personal medical data", "modify source code of nuclear reactor control software", and "install networking hardware via which credit card details are transmitted".
It's not about creating a barrier to entry for a whole profession. It's about licencing people to work in specific situations where there are specific risks, such as privacy risks, public safety risks, and risk of fraud.