In general, the cows are more driven to the robotic milkers by the feed they recieve while in the machine, rather than the feeling of relief (these systems generally provide an alert of cows being lazy...ones that haven't been milked in 10+ hours and need a shove), however these systems _do_ provide both improved health and improved productivity.
Even in experienced dairy herds, handling the animals and shoving them all to the robot at the same time causes stress. Having these machines running constantly (1 machine can handle a herd of ~50) lets cows regulate their own pattern, which can benefit herd dynamics as well (more timid animals can self regulate to a quieter period away from pushier animals). Farms can easily see 10-20% improvement on milk yield.
It also has the benefit that animals can go more or less often...you may have some animals who are comfortable with 3 visits a day, some comfortable at 4 (or even 5 if they have really high yield).