Cold War era planes also had a lot of problems. The YouTube channel “not a pound for air to ground” has some great content about planes from that era, and reliability was sometimes absurdly poor.

Avoid problems like humans putting water into the hydraulic system? [Virtually] no amount of money is going to solve that.

WW2 planes never suffered from confused sensors bringing the plane down and they were much much cheaper and effective. Look at the kill rate of the spitfire. Even heavy bombers had a decent chance of bringing down fighters.