Can’t read the whole paper but from the abstract, this sounds like an obvious case of correlation != causation. It’s possible whatever caused those regions to have access to western TV also helped foster businesses later, such as easy access to west German hubs or train lines or similar. In fact, their claim that the effects last through generations further weakens their argument since other East German regions would’ve gotten the same TV after the 90’s and should have caught up by now. Instead it sounds like something else is helping the original regions maintain their dominance.