Knock off the single quotes!

I have just been through a manuscript with a lot of inappropriate single quotes. Now, I'm not one to shame singletons in general; standalone items and persons are perfect the way they are, and do not require a twin to be made complete. However, standalone quotation marks in inappropriate places are a black mark, or lack of one, and something up with which I shall not put. 

Single quotes -- and here I'm not discussing apostrophes -- are seldom used in American English. We've settled on the double quotes for quoted material, as a means of setting off someone's words, and we like it that way. Single quotes are almost exclusively used for quotes within quotes.

"Hot damn," said Barney. "This morning Betty said, 'Get your lazy ass out of this house!' Can you believe it?"

The British do it the opposite way, which is their problem. 

'Blimey!' said Barnabus. 'This morning Betsy said, "Get your idle arse out of this house!" Can you imagine?'

The rule for single quotes goes as follows, and I quote from the seventeenth edition of The Chicago Manual of Style (chapter 13, verse 30): 

Quoted words, phrases, and sentences run into the text are enclosed in double quotation marks. Single quotation marks enclose quotations within quotations; double marks, quotations within those, and so on.

The problem, however, is that all of a sudden people -- and here I'm referring to professional writers -- seem to think that if it was not said aloud, it doesn't get the double quotes. Like so:

Sam went for his gun, the gun he liked to call 'Boom Hilda' for some strange reason.

This is wrong, wrong, wrong. There are two better choices than single quotes in standard text before we even get back to the double quotes. Words as words (like the name Boom Hilda used in that sentence) may be italicized, or they may be given no special treatment at all. Chicago 7.63 says: 

When a word or term is not used functionally but is referred to as the word or term itself, it is either italicized or enclosed in quotation marks. 

You can argue that Boom Hilda is not really being used non-functionally and leave it alone, no italics or quotes. Or you can italicize it, which would be the preferred method in books. Or, if you were texting the sentence or otherwise dealing in a method that allows no italicization, you would use double quotes. But there's no call for single quotes here. 

Somehow, though, just in the last couple of years, I get these manuscripts in which people cannot bring themselves to use double quotes except for directly attributable speech. How did this happen? I blame COVID. 

Well, maybe not, but it happened around the same time. I think the real problem with the pandemic was that it made everyone stupider. But that's a much larger problem, and one for another day.