Why should this have been the stipulation? Why not 2:1, or 5:1, or just an extra $42 million or whatever was needed? (Probably at least half a billion, honestly, but that's a hard bill to foot all at once.)
You mention that Jackson spent money on other things than sewers. Well, in retrospect, they were less urgent than failure of a basic service necessary for human life. On the other hand, redevelopment of a dilapidated area is, what, wrong? "You can't have any economic development, Jackson, because we're gonna make you spend all your money on sewers." We're supposed to think this is wise and compassionate move on the part of the state?
I don't deny that the city's investment in sewers could have been better. There are plenty of other cities who made the hard choices differently, and ended up with functional basic services. But that doesn't mean the right thing to do when you don't have to make such hard choices is to punish the people of Jackson for a history of inadequate investments. Sometimes you just have to roll up your sleeves and fix the mess, not sit there going "told you so!"
Indeed, Jackson has been trying, to an extent, on its own. Last year it allocated $80M in bonds to pay for improvements. (Not matched!) They have mostly installed new water meters because apparently multiplication is hard, though they still have problems: https://www.wlbt.com/2022/07/22/clerical-error-causes-1452-jackson-water-customers-see-spike-bills/. The lack of collection does speak to ineptness, but not the trivial ineptness of "they don't care" but rather "the vendor we chose for infrastructure liked gallons but we like cubic feet and we are so confused now because multiplication is hard". It's difficult to collect water revenues when you can't generate proper bills and therefore are hesitant to call out people who aren't paying.
Behind every disaster of human negligence, there are usually multiple culpable parties, and this is no exception.
Pointing out that this is so here, too, does not relieve the state of Mississippi from the duty of doing what it takes to safeguard the lives of its citizens. The point is not that because of lack of state investment, this was fated to happen. No! More competent state officials would have found a way to keep the system in better shape. Macon, Georgia is a prime example--they have absolutely world-class water treatment, despite being a smallish mostly-black relatively low-income city in the South. (They did get 3/4 of the funding for their water treatment plant from external sources--but this is to their credit, as it was an explicit goal of theirs.) The point is that with disaster looming, the state could have done a lot more, and whether the disinvestment was because of racism or politics or something else, or all of the above, it's still atrocious.
People have got to come first. When people don't get put first, and there's a long history of a certain group of people being discriminated against, and golly gee, look, they're most of the ones being affected again, the burden of proof is on the state to show that they're not mostly-indifferent for the obvious reason.