A four-bottle bar covers what people ask for. A six-bottle bar covers what you actually want to drink — because the two categories starter kits leave out, single malt and gin, are the two that reward a good bottle the most.
Every distillery in this box is small enough that the people who own it are the people who make it. One grows all its own grain on the estate and distils it on site, which almost nobody does. One is in Brooklyn. One bottles each agave field separately and names it, the way a winemaker names a vineyard. That is where the character in these bottles comes from, and it is the thing scale tends to average away.
It also means you can't price-check any of this at a chain store, because they don't carry it. What you're comparing is the liquid.