Often it's because they are being pressured by leadership not to. Leadership's bonuses and promotions are dependent on developers delivering value NOW.
Plenty of it is also on managers who simply aren’t competent to manage, of which there is a tragic abundance. If that really bothers you, move up to management and start doing the job better or go find a new job. Otherwise, not your circus, not your monkeys.† Just make sure to keep your papertrail.
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† Whereas the liabilities for screwing with production code outside your scope of work def should be. Though again, that assumes a management that actually understands what’s going on in its own shop, and isn’t just running around with its hair on fire 24/7.