I think PS2 is a nine year old game being supported by a two year old company. They were down to three devs in the dark days and had to build back up from virtually nothing all the while supporting this behemoth of a codebase they were unfamiliar with. At one point they said all of the engine devs were gone. As for automated testing, in a commercial environment with pure data APIs that's not a difficult thing to do. But in a 3D game it's incredibly complex and difficult which is why games heavily rely on manual testing. At least they can add "drive vehicle beneath water in biolab. Expected outcome: vehicle does not float into air" to their scrips, lol