It may be true that Amazon prices average the same or higher than brick and mortar. But some stuff you can't find locally, or as easily, and for me, I can find things on Amazon for a lot cheaper, especially if I buy in multiples or in bulk. I get delivery averaging less than $1 per delivery no matter what the weight. I have cases of 'monster energy' drinks delivered that cost about 25 cents per can cheaper than locally, even at Costco, all of it hassle free, and a lot of stuff is sales tax free, saving me at least 8.25%. Perishables like dairy, meat, vegetables, etc are almost always more expensive on Amazon, but even then, you can still find bargains.
For people like me who have arthritis or other health problems, Amazon makes life a lot easier and it saves me some money, sometimes a lot of money.