The problem is that the more expensive unskilled labour becomes, the more incentive there is to find alternatives.  

Our local Wal-Mart stores finally installed self-checkouts.  Our Superstore has 8 self-checkouts and only one cashier for 20 items or less.   I just went to a regular McDonalds for the first time in two years.  They had 6 self-order/payment machines and only one station for ordering/paying at the manned counter.  My TD branch has 8 teller wickets, but only two are manned at any given time.