Reliability is not just for nuclear power stations and air traffic control; more mundane applications are also expected to work reliably. Bugs in business applications lead to lost productivity (and legal risks if figures are reported incorrectly), and outages of ecommerce sites can have huge costs in terms of lost revenue and damage to reputation.
In many applications, a temporary outage of a few minutes or even a few hours is tolerable, but permanent data loss or corruption would be catastrophic. Consider a parent who stores all their pictures and videos of their children in your photo application. How would they feel if that database was suddenly corrupted? Would they know how to restore their collection from a backup?
As another example of how unreliable software can harm people, consider the Post Office Horizon scandal. Between 1999 and 2019, hundreds of people managing Post Office branches in Britain were convicted of theft or fraud because the accounting software showed a shortfall in their accounts. Eventually it became clear that many of these shortfalls were due to bugs in the software, resulting in many of these convictions being overturned. What led to this, probably the largest miscarriage of justice in British history, is an assumption by English law that computers operate correctly (and hence, evidence produced by computers is reliable) unless evidence exists to the contrary. Software engineers may laugh at the idea that software could ever be bug-free, but this is little solace to the people who were wrongfully imprisoned, declared bankruptcy, or even committed suicide as a result of a wrongful conviction due to an unreliable computer system.
In some situations we may choose to sacrifice reliability in order to reduce development cost (e.g., when developing a prototype product for an unproven market)—but we should be very conscious of when we are cutting corners and keep in mind the potential consequences.