The thing with software is that you need to feel the pain in order to learn something. For example, when you lose all your work due to a bad HDD, you learn the importance of backups. But we also learn from others telling you that you need backups. So you make a copy of your data, but on the same hdd. Because you really haven't learned the lesson. Same with test driven development, you can have an entire career without software regression bugs, so you have no reason to use TDD. No pain no gain!