This thread is an eye opener for me too. Do engineers not get trained on their legal obligations? My company is old and not a tradition tech company but we have been running workshops on the issue for years. Even if they don't, what about their legal teams? Or CI tools to scan for licence violations? Some of the responses here are so naive it's crazy. I hope no one is identifying the companies they work for.
But that's something entirely different from small code snippets, changed and adapted to solve the same problem a thousand other people already had. Nothing else are developers doing going on GitHub, StackOverflow or any other website to find answers to their questions. That's not naivety, that's how coding works (partially). If you would have to re-invent the wheel everytime you build something new, good luck.
Snippets aren't exactly defined but I see them as more than just a single line like "here's how to flatten a list in Python", it's some functionality - e.g. an algorithm implementation or some task.