Doesn't it all boil down to economics in the end? When I worked at AOL, QA was very important/valued because our SW was shipped on CDs (I know, I know), and every bug/update cost us users because we had to download an update at modem speed. Now that I work on a web development team, bugs are easily fixed by an update. So who cares if there's a bug? We can just update the site. There are other costs, of course -- if we tolerate lots of bugs and tech debt, making development slower, we will evenually have our lunch eaten -- that's economics too.
Users/customers accept a certain level of quality, and it doesn't make short-term economic sense to provide more.
I've seen the kind of mistakes that entry level employees make. Trust me, they will, and they will be bigger, worse mistakes.