There are very few people out of college who can implement a red-black tree on a whiteboard. Heck even those who just finished the data structure course while

There are very few people out of college who can implement a red-black tree on a whiteboard. Heck even those who just finished the data structure course while still in university. Even with the algorithm book open in front of them I doubt most developers can have anything working and good implemented in one hour. If you've spent the last 10-15 years writing code every day you can review your data structures course book before an interview and do better than most fresh graduates. Ageism is real I know lots of people >40 and >50 who hold good jobs and are also able to get good jobs if they end up being laid off for some reason. But then there are also people in their twenties who have a difficult time getting a good job for whatever reason. There are lots of factors.