To be fair, whether or not the cheaper version would do the same job is also not known in advance. There's also the fuzzy edges of what it means to "do the same

To be fair, whether or not the cheaper version would do the same job is also not known in advance. There's also the fuzzy edges of what it means to "do the same job". All chairs ostensibly "do the same job" of providing you somewhere to sit. But there's variance there. Just like all turing complete programming languages do "the same job" at some level. But we'd all be more productive in your choice of high level language over any processor-specific assembler. Then it becomes a matter of asking when does it transition between appropriate and luxury. Which grain of sand makes the pile?