my quick guess is that aside from strange accounting, it could well be that there is a lag. it takes a while to see the results of tech change in a service workplace. my experience with it is that, initially, you invest quite a bit of time in learning how to use the damn technology--upping the wages paid out. plus, you get a lot of resistance and a great deal of folks who have no idea what they're doing and how the technology can work for them.
you numbers folks: how exactly *do* they measure productivity? i mean, how do they account for, say, increased spending on products/traffic which makes the staff you're operating with appear more efficient. e.g., you have one waitress taking care of the floor during slow season. same waitress on floor as it picks up but isn't quite busy season. waitress is working hard, making the bucks, is tired but the wad of bills in her pocket is the reward. (productivity numbers are going to look good at that interim point). when it gets busier you add one or two more servers, a fourth part time for the rush hours. productivity goes down.
but then again i could be fucked and this is simplistic thinking since i have no clue how the bls measures this and didn't take time to look to see if they have some explanation.
kelley