but American singers also tend to sound more British, because they often sing without rhoticity, i.e. without pronouncing R’s that follow vowels, and are not followed by another vowel, e.g. pronouncing “larger” like “laja”

Because singing is basically its own accent.

🎶 Never moind I’ll foind…🎶

I’ve read it’s because singing and speaking are handled by different parts of the brain. Accents are regional, inside your head as well.

Imagine singing in Brummie