It's not just that. I use a fairly obscure dietary supplement. It's a crap shoot whether or not my local pharmacy has it in stock on any given day, and the only way to find out is to physically go there. If I factor in the cost of my time, buying local is orders of magnitude more expensive than Amazon, where I can place an order in under a minute.

I am astonished that brick-and-mortar merchants haven't banded together to get someone to build a decent e-commerce front end for their local stock. That would be a killer app.

I disagree. Delivery time is rarely ever a consideration for me. Convenience, large selection and the knowledge that I will be made whole in case issues arise without have to expend significant effort are the main reasons.