It's because none of it is secured, and the US has a shit load of infrastructure that all has its own independent systems. Even a tiny percent being hacked per lifetime will be constant hacks in the news.
Independent systems have their own problems but also benefits. The trendy word for this is ‘decentralized’. IMHO, I’d prefer we don’t have one big system. At least when the pipeline was shutdown it didn’t affect the entire country.
Theory: running the same system in pre-internet style would add overhead in salaries and delays that's more costly than being down for a few weeks after a hack.