Noticeably, though, the colours don't date the equipment. 20 years ago the colours were the same, and 20 years from now it is very likely that the brand new ones will still feature the same colours still.
That hasn't been the case for passenger vehicles. They are famous for having a colour available this year and gone the next, so if you have one of those no-longer-available colours it sticks out like a sore thumb as looking old. Which is what I believe the consumer truly fears – owning a car that looks old and dated.
The blacks and whites have remained consistently available, so it is far less risky.
From a buyer's perspective there's still a choice of color if you have no allegiance to brand, but the monochromatic tribalism of each brand (and their loyalists) is strangely fascinating.
Case in point. The last of the ACGO tractors in orange now look old and dated even though the otherwise _identical_[1] Massey Ferguson tractors from the same era still look relatively modern.
[1] Technically they had different engines, but that isn't visible anyway.
Once you see it you can't unsee it and it starts to look very ugly very fast.
1. Flat vertical panels are a no-no. Adding creases increases buckling resistance.
2. That's a hugely important area for cabin noise because the side mirrors cause turbulence and the vehicle body needs a channel to constrain the turbulent flow and flex as little as possible near the door seals.
3. The skin needs to expand outwards from the line of the pillars to fit the window mechanisms, the handles/locks, and the side impact protection without intruding into the cabin space.
4. It makes the car look more sporty and interesting. The technical term for the crease itself is "character line", and it's the main reason why the Corolla has one. It's visual reinforcement for the modern standard combo of low hoods-high trunks that's considered attractive styling.
5. The greenhouse (cabin) narrows towards the top for rollover safety and aerodynamic reasons (a.k.a tumblehome), and this needs to blend with the rest of the body in a visually appealing way. The cybertruck is a good example of how unusual it can look if this is just a straight line on the body. Here's a comparison between the current design and an ai-generated "rounded" design [2] [3].
[1] https://file.kelleybluebookimages.com/kbb/base/evox/CP/44005...
[2] https://www.motortrend.com/files/67a2770e2906d20008bad29f/1-...
[3] https://static0.carbuzzimages.com/wordpress/wp-content/uploa...