Tesco's wuff attitude towards dogs

Just returned from a short visit to our local Tesco. An over-zealous Advance security box-wallah was po-facedly telling a young woman that she couldn't leave her Jack Russell puppy tied to a rail outside the store. When asked why, he fell into 'more than my job's worth' mode: only following instructions, nothing against dogs, etc. Paid not much more than minimum wage, he probably gets his fair share of crap - and to be fair to the woman, her response was bemused acquiesence, rather than outright hostility or abuse. But since when did it become a no-no to tie a dog up outside a shop? Not very considerate, Tesco. After all, you allow us to insure dogs and probably make a tidy profit selling everything necessary for canine health and welfare, from dog biccies to scented poop bags, so why not let a dog wait outside while its owner is adding to your profits?