I think you are missing several points. For starters, the tendency to replace people with interfaces in customer interaction is due to cost and scalability.

Regarding customer satisfaction, the issue is not having to deal with another human or not. Replace check-in counter personnel with robots, and the result will be the same because the problem here is not human interaction but waiting in line. The issue boils down to value: perceived value, net value and expectation of value. Frustration only arises when perceived value is below expected value.