One box of aspirins

Today I went to Boots to buy aspirins and I was told that I can only buy one box at a time. A first, as I usually buy two boxes at a time. I was also given instructions how to used them - since it clearly looked like this was the first time I bought this most rare and unusual product.

I can only assume that the reason for this measure is to prevent an overdose of aspirins. All it did was to make me believe that I was being treated like a complete moron. Even with my lack of belief in mankind, surely no one accidentally overdoses on aspirin? And what's more, if you actually want to do it, all you have to do is to go to another branch!