My experience has been that you have to pay extra for a dumb TV right now, likely because of issues of scale. My last TV was an NEC E-series Commercial Display. Aside from not being encumbered by any smart-features, it has a serial port on it, to make automation even easier.

But I could have saved a lot of money by going with a conventional Smart TV, and it would have been easier to shop for it. Commercial displays aren't hanging on the wall at your local Best Buy, although they might be hanging on the wall at your local bar, restaurant, bank, etc.