Well, D&D also has Lesser Animate Dead, which doesn't require the 25 gp, but functions almost exactly the same - the only real limit is that the raised creature has to be size Medium or smaller, where as Animate Dead has no limit on size. So essentially, it costs a little bit of onyx to raise a human back from the dead. A very small price.
And then those skeletons (we're assuming skeletons, right? Zombies are useless outside of combat in contrast to skeletons) can work infinitely without becoming tired, since skeletons are immune to fatigue. They pay for themselves quickly, assuming we're being forced to use Animate Dead and not its lesser casting.
We could also animate horses and other laboring animals. We can go back to horse-pulled wagons for most of our transportation, and we wouldn't have to spend money on oil or metal or plastic for cars. We don't need to feed them either.
Also, bones are pretty light. We could transport skeletons very easily to one another when we need some more.
The only real cost at this point is raising and training necromancers, which would require teachers, classrooms, etc. But I mean, I figure it wouldn't be any harder to animate a skeleton with magic than it is to make a Powerpoint. We could teach kids through their basic education system how to animate dead, so by the time they enter college, they can raise their own dead and control them.
Eventually, we'd have limited our only purpose to raise and control dead. All other jobs are taken up by skeletons. Moral conflict may crop up when we realize our purpose is really, really small, but I mean, we have computers and artificial intelligence doing so much for us right now. It wouldn't be significantly different. And if we had technology behind us, too, we'd still need innovators to create that as well.
I'm pretty sure the concept of Law having limits was a translation error. -Wanderlustwarrior