I had a friend who sold software to run generic dollar stores. It was fully integrated POS -> inventory, etc. He was making a ton of money traveling to tiny towns across America.
It's extremely common for these companies to consider their POS/supply chain software is a core competency. So Major Dollar Store A would want to make absolutely sure that none of their code changes would be made available to Major Dollar Store 1, even if it were mundane stuff like tax code changes.
On one hand, it's good money, because it is such an integral part of their business. On the other hand, it can be tedious to redo the same thing after the sales staff sells the same customizations with minor differences.