They could make salary increase lineary not exponentialy. Since now you pay tax squared cause of exponential salary and luxury tax...
Or they could just leave things as they are. If people are training players that 99% of managers cannot afford because they're either sacrificing for the NT or just too foolish to act sensibly, that's not good reason to throw out the economy as it is. If anything, the best fix to the economy would just be eliminating U21 and NTs entirely, but of course there's enough of the user base that would revolt that it'll never happen. But for game design purposes, if you eliminate salary concerns then there's no point in even having an economy.