No it's because a piece of software with a few hundred thousand lines of code has a state space that boggles the mind. And then that software interacts with a dozen other services of similar size. And then new features need to be added every few weeks. It's completely incomparable to wiring up a normal house.

In buildings with nontrivial electrical systems, shit hits the fan really quickly too. Just look at the absolute mess that is the fire prevention system in Berlin's new airport for example.