> I am trying to understand the rationale behind this. Is there some industry or region where Long, Lat is the customary way of representing a location?

Historically, cartography was Lat,Long (1). Then software developers took over, and their natural mode of thinking inherits from thinking in x,y coordinates in 2d-graphics on the computer screen, so Long,Lat started to dominate in software. And now software dominates everything.

Here's a take on the history: http://docs.geotools.org/latest/userguide/library/referencin...

(1) This is from 1983, but the Lat,Long practice is much older https://en.wikipedia.org/wiki/ISO_6709