Why the environment does more design work than the requirements do
How conditions rather than specifications shape an outdoor machine.
A written specification tells a designer what a machine has to do, its load, its speed, its accuracy, but on any machine meant to work outdoors, the surrounding environment, the mud, the vibration, the heat and cold, the dust and rain, ends up deciding far more of the machine's actual shape, materials and construction than that specification ever does.
A machine that works indoors and a machine that works outdoors are different machines, and the difference is not weatherproofing, since weatherproofing suggests a coating added at the end to an otherwise finished design, when in practice the environment has already reached into the choice of every bearing, every seal and every fastener long before the design could be called finished at all.
Why the same task looks completely different once the environment changes
A written requirement describes the task a machine has to perform, but it very rarely describes, in the same level of detail, the conditions the machine will have to perform that task inside, and it is those conditions, not the task, that end up dictating the great majority of real engineering decisions once a design actually gets built. Two machines built to lift an identical load at an identical speed can end up looking almost nothing alike, one built to run inside a clean, climate-controlled building and the other built to run outdoors through mud, dust and a genuine seasonal temperature swing, and the difference between them traces back almost entirely to the environment each one has to survive rather than to any difference in the underlying task itself, since the task, on paper, was identical for both.
The muddy-field-errand comparison
Walking to a shop a few streets away on a dry city pavement asks almost nothing of a person's choice of footwear, ordinary trainers handle the job without a second thought, since the task, walking a short distance, barely constrains what gets worn to do it. The identical errand, walking the same short distance to reach a shop, becomes a genuinely different undertaking the moment it has to cross a wet, muddy field instead of a paved street, suddenly demanding boots, waterproof trousers, and a good deal more care about footing, none of which the errand itself asked for, all of which the ground and the weather did. Someone who packed for the walk purely by thinking about the errand, buying milk, rather than about the specific ground they would actually be crossing to do it, would turn up dressed for the wrong problem entirely, and a machine specified purely against its functional task while the environment it will actually operate in gets treated as an afterthought makes exactly the same mistake, just with a slower and more expensive way of discovering it.
Where this shows up hardest in outdoor equipment
The gap between an environment-shaped design and a requirements-shaped one is easiest to see in the smallest components, because those are the ones a requirements document is least likely to say anything specific about at all. A connector chosen purely against the electrical job it has to do, carrying a given current at a given voltage, can be a perfectly ordinary, inexpensive part indoors, where it never has to resist vibration shaking it loose, moisture bridging its contacts, or dust working its way in past a seal that was never specified because indoors nothing demanded one. The identical electrical job outdoors needs a connector built specifically for a vibrating, uncontrolled environment, one that resists all three hazards at once, a part that costs meaningfully more, takes up more space, and exists purely because of where the machine has to work, not because of what it electrically has to do, and a bill of materials built by working strictly down a functional requirements list, rather than by also asking what the actual operating environment will demand of every single part on that list, systematically underspecifies exactly this category of component. The same story repeats itself at the level of bearings, fasteners and seals, where an indoor equivalent chosen purely against load and speed is quietly swapped, once anyone actually walks the design through its real environment, for a part rated additionally against corrosion, temperature swing or repeated wetting, none of which the original functional specification ever mentioned because none of it was ever the specification's job to mention.
The number that matters here
A connector or fastener rated for an ordinary number of mating or tightening cycles indoors can need a substantially different, environment-rated equivalent to survive an identical electrical or mechanical job outdoors, one built additionally to resist vibration, moisture ingress and dust, and the underlying job the part is doing has not changed in the slightest between the two versions, only the conditions it has to keep doing that job inside of.
What this changes in practice
Reviewing an outdoor machine's design against its written requirements alone checks only whether the machine can do its job, it does not check whether the machine can go on doing that job in the conditions it will actually be asked to work in, and the two checks are genuinely different exercises rather than one implying the other. A thorough outdoor design review has to walk through the actual environment deliberately, the temperature range across a full year, the worst realistic exposure to water and dust, the vibration a rough surface will feed into every fastener and connector, treating each of those as its own explicit design input rather than trusting that a machine built to satisfy its functional specification will automatically cope with whatever ground it happens to be set down on. The rest of this set follows that same environment, mud, dust and the field itself, through the specific ways each one reaches into a design that was never written down as carefully as the functional requirements sitting above it on the same document, and by the end of it the pattern repeats often enough to stop looking like a series of separate surprises and start looking like the single, entirely predictable cost of building anything meant to leave a clean, controlled building at all.