I'd see a Zone of Truth spell as working almost exactly like polygraph tests today -- unreliable, proven wrong once or twice in big famous cases, and inadmissable in court. If I can make a Will save against it and succeed -- or worse, if I can pay somebody to modify my memory (per the spell) so that I can truthfully say that I don't remember doing it, this spell is, while not useless, not something the courts would want to use.
And yeah, a Fireball is deadlier than a hand grenade, so I'd imagine it's regulated pretty closely.
If you're someone who casts spells by a way other than study (a d20 Past sorcerer, for example), you might have to register yourself as a known spellcaster, because there's no way for them to prevent you from learning fireball.
I can see even Cure spells having trouble. As soon as you've got a (game-mechanics-wise) foolproof system that enables the rich to recover from any injury while the poor have to make do with Treat Injury checks, you're just asking for trouble. Governments might try to regulate Cure spells as a way to stop rioting in the streets.
Any professional sports association would have to start packing the field with Detect Magic items or casters in order to disprove claims of performance-enhancing magic. On the other hand, police and military forces might start packing enhancement bonuses onto their units as often as possible, unless treaties with other countries or international watchdog organizations forbid the use of such spells.
Necromancy, and in particular incantations that can raise or animate the dead, are bound to be ugly. My guess, offhand, is that in order to avoid a massive load of legal problems, most governments would declare that anybody who died for longer than 24 hours and was then brought back by magic, or anybody who is raised as self-willed undead, is considered to be deceased for purposes of contractual law -- ie, they lose their land, they no longer hold any office they held before, and so forth. Some crazy rich folks might use this as a loophole -- they have themselves killed, then raised, in order to avoid legal scandals, and they will the money to a nonprofit organization that they themselves then take over later.