They're becoming pretty commonplace. A friend runs a farm that uses them. The cows come in to be milked when they want to be, which averages about 2.2 times per day, they enjoy getting milked. A back scratching machine gives them a rub (which they love) and they stroll leisurely back to their paddock to eat more of their favourite thing; grass.

Staffing costs are much lower along with the subsequent disasters and animal problems caused by thoughtless staff. The cows are happier than ever and milk production is record-breaking.