Because these results can show more information than just a single bit?
The result might not just show “not worth digging” vs “worth digging”, but something like “the gold will flow for 4 years and then only trickle for 2” vs “the gold will flow for 8 years and then nothing”.
The result might not just show “not worth digging” vs “worth digging”, but something like “the gold will flow for 4 years and then only trickle for 2” vs “the gold will flow for 8 years and then nothing”.