While this is true for some engineering fields it's mostly not true and I think that's a good thing because credentialism is bad actually.
Also, architects are not even engineers.
If I want someone to do work, I want them to be licensed/certified. If they are flagrantly unsafe, I want a licensing board or similar to be able to strip that person of their ability to practice that profession. This raises public perception of the profession as a while, avoids a market for lemons, and gives some baseline.
There are too many decisions in life to be able to spend an hour (or more) researching every option. Credentials allow a framework of trust - I don't have to decide if I trust every single engineer; if they have passed their PE exam and not had their certification taken away that is a starting point.
You're just arguing that you want to outsource your own decision making. You actually should interview your candidates before hiring them, whatever credential they have, because it actually is your job to ensure you work with high quality individuals.
Credentialism basically allows the sort of low effort that you're describing and causes many places to rely solely on the credentials, which are obviously never sufficient to find high quality individuals.
What are the jobs you're day dreaming about that require PE exams? I'd bet that requirement is much less common than you think.
So, how complex is software production? I’d say that there are seldom best practises but often good practices (in example DDD, clean code and the testing pyramid) on the technical side. And then a lot of exploration on the business side (iterative development).
So is a certificate of value? Maybe if you do Wordpress templates but not when you push the boundary of LLMs. And there’s a gray zone in between.
Credentials are insufficient for all of those. A credentialed plumber or electrician could flood or burn down your house and it might be hard to figure out the root-cause, so the credential slips. You still have to do due diligence to find competent people.
I'll admit that for certain things which are easy enough that you can write down procedures for them that a credential can be valuable, but there are a reasonably small number of those things in the world and even when you do write the procedures down you're usually significantly constraining the type of project that individuals in that field can undertake. That constraining is a very important trade-off to consider when thinking about whether a credential is helpful.