Many smart TVs have firmware that interfere with your ability to switch sources using the remote for your cable service provider, or causes it to default to a specific source menu or app, or auto-switch between sources when it thinks it's "detecting" them, even if you were actually using the other one.

And older people don't know how to navigate the new user interfaces that come pre-installed on these smart TVs, especially if they have several connected devices on different ports. Have you had to walk a customer over the phone through using the Video Input button on their cable service remote, only to discover the TV software doesn't allow 3rd party remotes to access the video input menu; because only the TV remote they lost is able to access that menu?

Or had to look up an article on a customer's brand of smart TV, and walk them through disabling specific tv settings buried in their menu that prevent the TV from properly detecting and switching between sources, or having to mess with the TV closed captions, because they're somehow interfering with the closed captions settings on their cable box.

I have. SmartTV software is occasionally a nightmare to negotiate with when trying to get it to work with a customer's STB or their wifi, or what have you.