Sorry for the wall of text but I needed to get this out of my system.
I only use the so called "express lane" or other supermarket equivalents if there are at least 2 trolleys waiting at each manned till (unfortunately my usual supermarket has recently replaced about 2/3 of its tills with unmanned ones. it is ironic that the “express lane” frequently forces you to wait for attention from a shop assistant because it is “verifying item weight”, often causing it to be far slower than waiting 5 minutes to use a manned till.
The supermarkets all have signs up saying please bring your own bags, I always bring my own bag, a large backpack which also contains tools and other equipment required to strip and repair a Bicycle or Computer which I frequently require but is plenty large enough to hold my shopping as well, and strong enough to hold 20 kilos without problem. You cannot place a bag like this in the bagging area without assistance because the scales detect that it weight a few kilos and decides you are trying to steal something from the shop (ignoring the fact that if you wanted to steal something you would simply not place it on the scales), you cannot place your shopping loose in the bagging area then transfer to the bag without complaints from other people waiting to use the checkout so the supermarket obviously wants you to use the disposable carrier bags, if the supermarket is busy (and if it was not I would wait for a manned till)I place my shopping in the carrier bags then move to a seating area and transfer the shopping to my backpack before placing the carrier bags in the bag recycling, a waste of time and the energy used to recycle the bags.
Conclusion, the so called “express lane” is a conspiracy by the major supermarkets designed to reduce labour costs and annoy paying customers by forcing them to waste much more time than if there was a real human (or other well trained primate) at the till(how else can you explain all supermarkets starting using them within such a short period). The trend of one person to 6-10 unmanned tills is way too low, at most it should be 3 tills for every person, preferably 1.