I run the software a building site needs before its first worker walks through the gate, usually between six and seven in the morning.
The first system I wrote that anyone relied on recorded which excavator had been on which job, for how many hours, so that a civil contractor in Newcastle could charge its clients correctly. I had finished a software engineering degree at Calderwyn Institute of Technology in December 1998 and joined Garrowby Civil in February 1999 as its second in-house developer. The site supervisors filled in paper dockets at the end of a long day. If my screen took longer than the docket, they went back to the docket. That was my first lesson in reliability, and it had nothing to do with servers.
A site manager at a locked gate with forty workers behind him does not care which component failed. He needs to know who has completed the induction, who holds the right permit and whether the day can start. I judge our engineering by that moment first, and by the elegance of our architecture a long way second.