It's just lack of competitive pressure. I bet if you investigate you will find there are only a couple of suppliers that have the bowling alley market sewn up between them.
Work out how many bowling alleys there are and how many of them are in the market for an upgrade or a fresh install, trying to get to be the king of that hill is a lot of work and risk for not really life changing rewards compared with what a self-avowed SRE could make just pulling paychecks
There is not much to compete for. Competitive pressure doesn’t magically spawn out of thin air.
You’d die on the back of unreliable operation and relatively high maintenance. A DIY system built off of cheap ESP32s is never going to be reliable enough. The system as described above is the sort of thing I would happily operate for myself, but would never attempt to sell as a product. Anyone who’s tried to hold together a few dozen ESP32-powered IoT devices will likely attest—they’re very impressive for their cost, but hardly reliable on the scale of years.