Those workmen have nothing to do with “the compiler.” To continue your peculiar analogy, the compiler would roughly correspond to a cement-mixer: a necessary, but passive, tool for the job that is used by every single job of its kind.
(Have you ever...)
For a project consisting of more than a quarter-million lines of (not Perl...) source code, lasting nearly ten years ... yes, it did.
Even though the thought of meticulous planning somehow earns responses of “why bother” or “software is different,” I'll stick to my experienced guns.
Just as you can design a physical machine, or a building, or a golf course, or a shopping center “on paper” in advance of building it, and even accommodate fairly on-the-fly changes to those plans “on paper,” you can design software systems in advance, and keep those paper-plans up to date.
When people spend $30,000 or so on an addition to their houses, they take for granted this sort of discipline. Yet when they spent $3,000,000 (maybe without quite realizing that they're doing it, or that they're wasting more than half of it) on a software-project, they get lured into thinking that somehow the rules have changed. No, they haven't: you're still paying someone to do something, and you still expect to have reason for confidence that you'll actually get it.
When you are “in the trenches” on a project, as most “Perl programmers” are, you just don't see the financial burn-rate. You don't think of your salary as an expense. It might never occur to you that the company is spending a million a year on what you're doing, but that's actually just a small project: it could be much more. Software projects are actually very-big capital investments that traditionally do not get the same scrutiny and treatment that other smaller investments routinely receive. Don't ask me why...
So what does all this budget-talk have to do with testing? Everything! Physical construction projects look simple as you whiz past them at 65mph on the freeway, but they're meticulous undertakings. That's why you whiz across thousands of bridges in the course of your travels and (almost...) never fall into the river. Software has never had that sort of track-record, and here's part of the reason why.