In the trades, there are the general contractors who submitted the lowest bids and hire nothing but the lowest bidders. Everything is rushed, and the poorly crafted McMansions are the result.
Then there are the true craftsman. The dudes who stop every few minutes on the way to their job site to point out the sloppy, incorrect work to the younger guys. And you want to talk about "code review"? These dudes would relentlessly hammer the methods you used for any task, to ensure you did it efficiently and cleanly. Most people, for instance, have no idea how to efficiently use a shovel to dig a deep hole. There is a technique to it that makes it much easier, faster, and less tiring. Abstract that up to every single task on a construction site and you can begin to understand what these folks knew.
Of course, the majority of construction jobs nowadays will have you working for one of the "quick and dirty" companies. Even if you are a true craftsman, you will be at least somewhat surrounded by sloppy workers who never learn proper technique.
It's kind of like looking at code written by the really bad outsourcing companies who hire overly specialized people who only know recipes.
We are able to teach basic math to everyone, if badly at that. I doubt programming is such big of a jump.
This makes me suspect you haven't had much exposure to trades. Getting good... really good... at welding, or cabinetry, or stairbuilding, takes at least as much dedication and skill as getting good at programming.
Note that there are plenty of programming jobs and tasks that are boring, repetitive, easy to do, and of little impact to the underlying system, that really need to be done by human. Things along the lines of modifying a report, extracting some data on a request from other departments, or adding a button to an Android application.
Somebody still needs to do them, because they're often virtually impossible to automate away, but you don't want to waste a really good programmer on something like that, and a really good programmer usually will not want to do them either.
That attitude certainly explains a fair few 'legacy' systems I've seen.
Also, no shame to work a trade job at all. Not sure where people get that idea?!