At this level of dysfunction, installing git won't do anything. You need a holistic change in thinking which starts with convincing people there's a problem.
Yeah, this level of dysfunction takes years to cultivate.
You need the “Dead Sea effect” to be in effect long enough that not only have the good people left, but for them to have been gone long enough that people rising into management have never even worked with somebody competent so they don’t know there’s a better way
I am occasionally on firefighting projects for customers.
It's super hard to get out of this mess.
The code base has gone to shit, customers are often passed enough that they want functioning code NOW, the reaming developers are bottom of the barrel, management is either cause of the problems or has now clue.
Getting out of that is difficult especially if management doesn't understand it has to change first.
Years, and a special kind of myopia in leadership to not see the seeds sprouting. It doesn’t happen quickly, but once established is very, very expensive to fix.