we're a bit past this point by now. Most people npm install some package, use webpack/minify to bundle it up, and poof no copyright or attribution. Even though both MIT and BSD (the most common licenses) require this. Even if you do the magical incantation to retain comments in your bundle, many packages don't include copyright in the comments. They include it in a LICENSE or README file.

Once upon a time devs cared about this sort of thing. Living through the '90s and then now... where devs just pick the default license (MIT?) that github puts on a repo is crazy. There is this cultural assumption today that everything is just a public domain free-for-all.