Supermarket sweep

Why is it that, no matter how many people are behind you in the queue at a supermarket, the till operator usually moves at a ridiculous and unnecessary pace? What I want is reasonably carefully packed bags, with fridge and frozen stuff together, tins in another, bread and other squashable items in their own bag, etc etc. But what I get is a mish-mash of shopping that will take twice as long to unpack, based on how fast my hands can move. It's as though there is some penalty for leaving the goods on the conveyor belt for more than two seconds. 

The cashier can see that you are struggling to get it all packed while making sure your toddler doesn't fall out of their plastic seat (despite being strapped in); they watch as you fumble to open plastic bags (if like me, you frequently leave the four environmentally-friendly jute numbers in the boot of the car). But do they help? No. They. Just. Watch. And then you pay and can almost hear them drumming their mental fingers on your head as you search for a loyalty card (do they realise that loyalty means they have to be nice?)... and then there's my frenzied digging around for coupons for Aptamil toddler milk (which is bloody expensive but reassuring, and, yes, I did breastfeed my daughter for as long as we could manage when she was smaller, so don't even think about guilt-tripping me any more than I have been).

Anyway, Waitrose... well, they go  m u c h  m o r e  s l o w l y and, frankly, it makes the whole experience relatively enjoyable when I can afford to go there. It's a shame Tesco and Sainsbury's (30 tills and only ever six open, the bastards), don't take note.