A lot of smaller startups lack long-term capital. You could be relocating for a job that isn't there in seven months. Relocating to join an established company that will honor your multi-year contract? That's one thing. But relocating for a company that may not be in great financial shape (and may have never even made profit) is another thing entirely. Uprooting your entire family for what could be a massive risk is a lot to ask, especially when employees can remote work to see if the job is a good fit for a year or two. Startups really should be offering more remote employment if they want to be able to attract more established talent.
I would also quibble with his cost of living calculations. He doesn't say whether or not these short trips involve walking or driving a car. Based on my knowledge of Louisville and the tenor of his post, many of them may in fact be car trips, which are much more expensive than walking or public transportation trips -- both financially and physically. If you live in a truly walkable area, you don't need a gym membership. Exercise is called living your daily life.
Old cost of living indexes just factored in housing and some other data, leaving out transportation. When you factor in transportation, often a households second highest cost (and highest in rural areas), many of these areas become much cheaper. We live in the DC area right on the Red Line and only need one car because of it. All of our trips this past weekend -- going to parties, to the movies, to stores, to get pizza -- either involved walking or public transportation. While my housing is assuredly more expensive than someone living in Louisville, my families transportation costs are incredibly low.
So when we talk about cost of living, we have to factor in everything. I'd still bet that Louisville is cheaper than NYC, but it's a lot closer when you apply an apples-to-apples comparison. This is particularly true when you compare housing in the same metro. Much of that exurban housing is suddenly a lot more expensive when you factor in transportation.