So:
- Humans make mistakes all the time and we happily pay for those by the hour as long as the mistakes stay within an acceptable threshold.
- Models/agents will get cheaper as diminishing returns in quality of results get more common. Hardware to run them will get cheaper and less power hungry as it increases in commodity.
- In all cases, It Depends.
If I ask a human tester to test the UI and API of my app (which will take them hours) the documented tests and expected results are the same as if I asked an AI to do it, the cost may be the same or less of an AI to do it but I can ask the AI to do it again for every change, or every week etc. Have genuinely started to test this way.