validation and approval processes. For safety critical engineering, it's nearly always been the case that the process design, oversight, documentation, integration, and testing of the work will take longer than the actual "building". That's by design. Nobody likes it, but it's the unfortunate burden of bringing the safest possible designs online.

Sure, we could all go faster and break things, but the public tends to start to frown on that sort of thing if it means people getting killed too often. To Musk's credit, he's no Stockton Rush and despite the joke seems to mostly follow good process, which is why he's frustrated with the speed. If you aren't annoyed by the speed of development, you are probably not following the rules.