[ppeetteerr]

The cost of keeping software up to date (e.g. latest practices) increases exponentially as the size of the software grows. When you have a company with over 100 contributors, and/or with many years of code, the value of maintaining some ugly bits becomes excessively high but the value of upgrading that software is not always quantifiable.

A rule of thumb is that you'll always have at least 2x or more code than engineers to maintain it. When setting priorities, you have to be pragmatic about which code to update, and which features to build.

That's probably why you're seeing so much old code.

By the way, as a freelancer, you may also be hired to maintain the ugly bits of a system. Full time employees generally work on building value, whereas freelancers are hired to take care of things that people generally don't want to hire full time employees to do.