[Pseudoscience-is-malarkey (OP)]

Why do archaeologists, paleontologists, animal experts, geologists, etc, usually have a penchant for wearing khaki shorts, khaki vests, and wide-brimmed sable fedoras?

[Bored chemist]

It doesn't show the dust / dirt.
The hat keeps the rain off.

[alancalverd]

Why do judges wear wigs? Kings and crowns? What is the significance of clan tartans? There's no official uniform but professional civilian pilots wear white shirts with black trousers and ties. Folk like to conform to a group "look" and both punters and TV producers like to identify the professionals.

[Bored chemist]

What is the significance of clan tartans?

Largely Victorian profiteering

[alancalverd]

.....says the man who has never worn green in a blue stadium, Jimmy.

[RD]

Why do archaeologists, paleontologists, animal experts, geologists, etc, usually have a penchant for wearing khaki shorts, khaki vests ...

Cheap army-surplus.