I've always thought it was a bit strange that in the US, the engineer who designs the mechanical parts of your car's brakes needs a professional license, but the engineer who writes the software doesn't.
Before you can license a group you need objective standards. Physical parts are easily translatable into standards with science and testable experiences. Software can fall into this category or they could be black boxes like AIs
Not mechanic as in the person that services brakes, but Mechanical Engineer as in the person engineering them.
Mechanical Engineers in the US are usually expected to be Professional Engineers (professional license) and in good standing with ASME, the American Society of Mechanical Engineers (professional society).
The people who need the P.Eng. qualification get it and the ones who don't need it tend not (why do all that extra effort if its not required). So that just means more civil engineering positions require it than mech eng positions.
For some types of software its the code development and testing process is highly regulated, for example aircraft avionics. In this case it doesn't really matter the qualifications of the person who wrote it provided the resulting code met all the process and testing requirements.