Guide
The work where the comparison is not about money
Updated
For a large category of work the cost comparison is irrelevant because only one of the options can do the job. Recognising which category you are in comes first.
Novel situations
A tool handles the distribution it was built for and fails outside it, often confidently. A person recognises that something is unusual and escalates, which is a capability rather than an absence of one.
If your work is mostly exceptions, the tool will produce plausible answers to questions nobody should have answered automatically.
Accountability
When something goes wrong, somebody has to be answerable to a customer, a regulator or a court. A tool cannot be, which means the accountability lands on whoever deployed it.
That is manageable and it has to be designed for. It also means supervision is not optional in those contexts, which changes the cost comparison.
Relationships
Work whose value is the relationship, not the output, does not transfer. A supplier who takes your call because they know you is not a process step.
This sounds soft and it is frequently the actual product.
Where the tool clearly wins
High volume, low variance, low consequence work with a clear right answer, where speed matters and mistakes are cheap and visible.
Most businesses have some of this, and it is where a first deployment should go regardless of what the wider comparison says.