I am guilty guilty guilty! I'm writing full stack and I have NEVER worked side by side with a more senior engineer or EVER had a code review or EVER taken a coding class. (Okay, I had one class in C in college 40 years ago.) Amazing that people actually pay me to do this. I tell them, "I am not qualified to do this, I do not have the right skill set," and they say, "Just give it your best shot." Then they ship it. For cryin' out loud! ...oh, and I never write tests. Conclusion: Never buy anything from a small or start-up tech company. You can be they cut corners.