You need overhead to run a business. Pointing to GP is nice for a company that can expect overhead to stay the same while they reap the benefits of increasing s

You need overhead to run a business. Pointing to GP is nice for a company that can expect overhead to stay the same while they reap the benefits of increasing scale, but all the large grocery chains in the US are already at scale. If there was extra net profit to be had by reducing overhead, they would have done so already.