They also generally are just better built. The expected hours of operation and MTBF of the components is generally much higher than consumer displays. Many of the ones I dealt with had metal cases and stronger glass.
They're expected to stand up to much more abuse or often be installed in places where they're inconvenient to service.
If you wanted to build a non-smart panel with the expected lifespan of a typical consumer TV a significant portion of the current cost could likely be cut if it were done at scale.
Is the "smart features" actually making money for the TV manufacturers?
A good question to think about. How can we, as consumers, incentivize the TV manufactures to focus on building good product that actually liked by users, and still making good money.
Very difficult to answer though...
You can already get dumb TV, they are often used for signage or other commercial purposes, but they cost a lot more than consumer equipment.