Devils advocating that somethings are without reason and that is an exception to the rule is a fairly weak straw man.

Not having a reason is a simplification that does not hold up: Incompetence, apathy, out of date thinking, because grey was the factory default colour palette(credit to fubarobfusco), are all reasons. It is a mark of expertise in your field to recognize these reasonless reasons.

Seriously, this happens all the time! Why did that guy driving beside me swerve wildly, is he nodding off, texting, or are there children playing around that blind corner? Why did this specification call for a impossible to source part, because the drafter is using european software with european part libraries in north america, or the design has a tight tolerance and the minor differences between parts matter.