society gains nothing by preventing a software developer from implementing ...

I see the point you are trying to make but I respectfully disagree. Technology is at the core of seemingly every field and at the core of technology is software. Will it result in direct bodily harm? Rarely. But indirectly the impact is certainly more substantial.

Take internet as an example. The significance of internet and information sharing cannot be disputed. Disturptions to information sharing can send ripples through services that provide essential services. Networking these days is accomplished Vida software defined networking techniques. And we are becoming more dependant on technology and automation.

I can see why the indirect risk is not as scary as direct risk, but you have to admit, as automation is growing and decisions are being made for us, regulation of those that build these systems should not be overlooked. Professional engineers have a code of ethics they have to adhere to and if you read through it you can see the value it would bring.

As a counter example to your "doctors are licensed to not kill people" - orthodontists, who move teeth around, pose no fatal risk to their patients. Should they be exempt from being licensed?

EDIT:

Just yesterday news was published by Reuters that Musk and managers at Tesla knew about defects of autopilot but marketed otherwise. If those working on it had been licensed, then negligence and decietfulness could line them up to lose their license and prevent them from working in this line again. It would bring accountability