Are we just shittier engineers, is it more complex, or is the culture such that we output lower quality? Does building a bridge require less cognitive load then a complex software project?
We're better at encapsulating lower-level complexities in e.g. bridge building than we are at software.
All the complexities of, say, martensite grain boundaries and what-not are implicit in how we use steel to reinforce concrete. But we've got enough of it in a given project that the statistical summaries are adequate. It's a member with thus strength in tension, and thus in compression, and we put a 200% safety factor in and soldier on.
And nobody can take over the ownership of leftpad and suddenly falsify all our assumptions about how steel is supposed to act when we next deploy ibeam.js ...
The most well understood and dependable components of our electronic infrastructure are the ones we cordially loathe because they're composed in shudder COBOL, or CICS transactions, or whatever.
Both IMO: first, anybody could buy a computer during the last three decades, dabble in programming without learning basic concepts of software construction and/or user-interface design and get a job.
And copying bad libraries was (and is) easy. I still get angry when software tells me "this isn't a valid phone number" when I cut/copy/paste a number with a blank or a hyphen between digits. Or worse, libraries which expect the local part of an email address to only consist of alphanumeric characters and maybe a hyphen.
Second, writing software definitely is more complex than building physical objects. Because there are "no laws" of physics which limit what can be done. In the sense that physics tell you that you need to follow certain rules to get a stable building or a bridge capable of withstanding rain, wind, etc.
Given hardware available to an average modern Linux box, it is hardly surprising that these bells and whistles were added - someone will find them useful in some scenarios and additional resource is negligible. It does however make understanding the whole beast much, much harder...
I'd say it comes from some of (order of most to least imo, but I'm only mid level so take what I say accordingly):
* physical processes have a fuzzy good enough. The bridge stands with thrice its expected max load. It is good enough.
* most software doesn't have life safety behind it. In construction, life safety systems receive orders of magnitude more scrutiny.
* physical projects don't have more than 20 different interdependencies; there's an upper limit on arbitrary complexity
* physical projects usually have clearish deadlines (they lie, but by a constant factor)
* The industries are old enough that they check juniors before they give them big decisions.
* Similarly, there exists PE accountability in construction
There are no big wins left in bridge building, so there is no justification for taking big risks. Also, in most software project failures, the only cost is people's time; no animals are harmed, no irreplaceable antique guitars are smashed, no ecosystems are damaged, and no buses of schoolchildren plunge screaming into an abyss.
Your software startup didn't get funded? Well, you can go back and finish college.