There are plenty of companies out there that really do nothing along the lines of best practices. No code reviews, no unit testing, no testing plans, no nothing, just by the seat of their pants.
Take this as an opportunity to get them to use a Continuous Integration platform and develop unit tests! Easy way to impress the powers that be and increase the quality and stability of your code at the same time
Edit: As for reason, I think they just plain aren't aware of the current tools out there that make CI and unit testing extraordinarily easy.
