So far for me 100% of candidates claiming self taught can barely code a for loop, much less explain at a high level how a compiler works or the difference betwe

So far for me 100% of candidates claiming self taught can barely code a for loop, much less explain at a high level how a compiler works or the difference between a heap and the heap. In most cases they don't even know the foundations of the language in which they are most efficient. Most people I know are also self-taught and read a lot of the theory. If they are self-taught, what in God's name are they using to teach themselves?