There was no OO before PHP 5 so you are missing the point.
Obviously you wouldn't write modern software like this but maintaining those old systems is a hell lot easier then those where people went nuts on OO and inheritance was used more lightly. Bad abstraction are worse that lack of abstractions, basically.
Either work on a modern project that has been build in recent years or if you have to maintain things, better go with something really, really old. Those in-between projects that don't seem to be totally hopeless but are still rotten, yeah that is there most pain lies.
Sure it depends depends on the specific project, everything can be abused but that is a totally different discussion.
Testing? You think the people with such horrible legacy code would pay me to write tests? I am happy if they don't want me to edit it directly on the live servers.
But yeah good point with the testing. I should have specified that I am talking about agency work, not actually caring about the software you keep alive.
Obviously you wouldn't write modern software like this but maintaining those old systems is a hell lot easier then those where people went nuts on OO and inheritance was used more lightly. Bad abstraction are worse that lack of abstractions, basically.
Either work on a modern project that has been build in recent years or if you have to maintain things, better go with something really, really old. Those in-between projects that don't seem to be totally hopeless but are still rotten, yeah that is there most pain lies.
Sure it depends depends on the specific project, everything can be abused but that is a totally different discussion.