This is not a phenomenon unique to film or darkroom supplies. Between "big box" stores with 40,000 square feet but no variety or selection, and the internet; local specialty stores are, for the most part, gone.
My wife sews and makes all of her clothes. She buys 95% of her fabric and notions mail order because all the local stores have is stuff for quilting and "crafts". Mostly low quality and over-priced. She also paints and gets most of her art supplies online, too.
Earlier this week, I needed new blades for my riding lawn mower. I called the dealer and was told that they don't stock those since they didn't sell that brand. I told them that I bought the mower FROM THEM and hung up. Ordered the blades online and they arrived the next day. Shipping was less than gas would have cost me to drive to this dealer!
If I need a piece of hardware or a light bulb that is not one of the six that Home Depot sells (this month), it's off the the internet.
I don't live in a small town. I am in a suburb of Dallas, and the Dallas/Fort Worth metro area has 6 million people. It's the same all over.