Good question. I think a big part of physical engineers' credential comes down to liability, which ultimately leads to civil engineering firms hiring contientious and responsible engineers. It's a internal feedback loop that the software industry tends to lack.
I'm not advocating for senseless beaurocratic hurdles, but you have to admit that standards for software have fallen as more people have entered the industry.
I don't agree that modern developers are less capable. If I had to choose between software developed to the best practices in 1995 and the same software developed to modern best practices, I'd pick the modern software in a heartbeat. What's changed is our relationship with software. Old school software did fewer, simpler things. The tools available limited what could even be realized and expectations for the end result were fundamentally different than we have today because they had to be.
I'm not advocating for senseless beaurocratic hurdles, but you have to admit that standards for software have fallen as more people have entered the industry.