I remember discussing this in operations class. If I recall correctly, the biggest issue with the single line approach is one of perception. Customers see a really, really long line and decide to skip shopping at a location. Despite the fact that this is more efficient allocation mode of checkout "supply" for the checkout "demand".<p>I believe Disney may have put some effort in masking the length of the single line to address this issue. Might be something that grocers could learn.<p>A couple factors, though, would seem to undermine grocers' incentives to change their queuing approach:<p>One is the need to maximize inventory on the sales floor. They would need to do a lot of reconfiguration to handle the single line. And that might potentially reduce floor space for stock.<p>The other issue is that grocery stores fill a core human need: food. We're going there regardless of the line configuration.<p>I'll bet some grocer out there could make a name for themselves by shaking up the traditional ways we shop. This queuing idea is one example. Would be a smart move in fairly commoditized industry..
In Walmarts in Mexico there are many 20 items or fewer registers; these are all fed by a single line. At busy stores during busy times these single lines can extend well over 100m. People complain about the long lines, but they do move quickly -- well, as quickly as anything moves here.
That time were there was an onslaught of erlang articles on HN there was one called something like "Erlang the movie", for some reason Erlang telephony videos make me happy :)