Public service: Some feel that it is their calling. They don't seek the profits of private industry. They want to ask not what their country can do for them, but what they can do for their country.
Or something like that.
Those people would have gone into public service anyway. Considering the lawyer archetype (soulless, greedy, etc.), that's probably one percent of graduates. Where do the rest of them go? A rare few head to BigLaw. Everyone else chooses between private and public sector gigs.
Choose no more. Choice is an illusion.