As Danny said, a lot of things in the RV industry don't make much sense "when compared to the automobile industry"... That is changing, or more likely, "morphing" with time...
RV's, especially travel trailers, got their origins as a part of the "manufactured housing industry".... Housing electrical standards which are primarily 120/240 VAC, are different from the automobile industry which is/was 6/12/24 volt DC, depending on the size of the vehicle starting and operating systems.
Those two industries "adopted different color standards". Housing: black hot and white neutral and Automotive: red hot and black neutral/ground.
The confusion comes from the federal government applying "Manufactured Home standards to the RV industry"... RV manufacturers have long "fought that "lumped together ruling" and in recent years, with the rise in motorhomes and class B/C RV's, have made some headway to break away from the "government mandated manufactured home industry"....
One of those changes was, around 2018, to re-identify electrical battery connections from "house wiring colors" to "automobile wiring colors" where the 12 volt system attaches to the battery... That, IMO, only makes sense...
And yes, I can't begin to count the number of blown reverse polarity fuses that have been a result of the "housing standard confusion with a car battery on the tongue of a travel trailer which is also charged by a plug from the tow vehicle"......
But, it is what it is and now, until decades from today, all the old "black/white battery cables" are in a salvage yard, a "double standard"...
Remember, however, that there are TWO electrical systems in your RV and both need to comply with some type of "standard"... In the 12 volt DC system it's red/black and in the 120 volt AC system it's still black/white while in 50 amp inputs to the power center, it's black/white/red (2 hot leads)... So, somewhere in YOUR RV, there's still going to be a "black ground connected to a white neutral/ground (typically on the chassis rail), so the "ground wire color is still "black and white/bare copper" depending on which electrical system you're connected to the chassis ground.....
As for the battery, take your pick, red and black or black and white... But remember, black is hot in one pair and ground in the other !!!!! Marking them so you can easily identify YOUR cable connections only makes sense...
