Just look at our voting count machines. You think something like that would be treated with extreme priority and would have a lot more security around it than it does.
If the priority was to build a good system. However, powerful government factions think that all government development must be farmed wholesale to private business, because of a twisted ideological belief in the market. Those private businesses are ruled by the ideology that shareholder value is the ultimate and only good, so they slap their products together as cheaply as possible.
The result of that toxic stew is that we can't have nice things.
Given the risk/reward and how cheap it is to do compared to a single B2 or a handful of F35's at least.
If there was an actual cyber war I am confident the US can hold it's own if it wants to.