Huh, thanks for the link. I swear that when I read that document (or a similar PSR) about a year ago, it specified that it didn't take a stance for method names (or maybe regular function names). I wonder why I thought that or if I read it someone else.
Thanks for that.
Frameworks, IDEs, and linters all follow the PSR-2: https://www.php-fig.org/psr/psr-2/ .
It is indeed common for new developers to not know or care about it, but most professional shops I've been to adhere to it unless they're working on very legacy code.