The problem is thinking that there could be such a thing as a license for software engineers in general. That would be crazy, almost like having to be licensed to write English. Software is applied to too many different domains and tasks.
What could work would be licensing for software engineers in certain specific domains. For example, we could require election systems software engineers to be certified for that field. Same with automotive software, power plant software, etc. etc. I agree that we should do this. But it's going to apply to only a small fraction of all software engineers, because licensing Web app developers is not practical.
Not practical, nor needed. A web app crashes? OK. Your customers get annoyed; your company loses some money; the world goes on. Losing money gives the company some incentive to get its act together, so it tends to be a self-correcting issue.
What could work would be licensing for software engineers in certain specific domains. For example, we could require election systems software engineers to be certified for that field. Same with automotive software, power plant software, etc. etc. I agree that we should do this. But it's going to apply to only a small fraction of all software engineers, because licensing Web app developers is not practical.