I think what you described would be a good definition of outcome. But, Who bills customers that way if you think about software providers? The prevailing models

I think what you described would be a good definition of outcome. But, Who bills customers that way if you think about software providers? The prevailing models are fixed fee , hourly fee or infra-spend fee. There is an argument to be made that SaaS tools tap the tool budget whereas AI agents can tap the worker budget of companies. I am looking to understand more nuances here.