Like it was said here, "hit or miss", I would place some of the reason for more or less failiures on two things:
- Who is the OEM?
- Where was it built?
Because, EU fella here, here's the record for the statistics of non-Smart TVs in the family:
- '89 JVC 22" Stereo CRT, main house TV and used every day for at least 2h, lasted until 2008 (wish I could still remember the model, can't find it by searching)
- '97 JVC 18" Mono CRT, still works though every single button on it has given-out and it's on its 3rd remote
- '08 LG 37" 37LH4000 LCD, still works and no issues with the lamp/screen (I bet because the energy saving + auto contrast adjustments are on since day one and are the best I've ever seen)
- '08 Samsung 19" 933HD LCD, still works (This thing is a tank, used as a kitchen TV and then Monitor hooked to computer+console+antenna)
- '11 LG 32" 32LH3000 LCD, screen has some discoloring at the center like a 20-ish cm circle but other than that works 100%
- '15 Samsung 32" LCD, works flawlessly while being used a bit carelessly I might say
The first ever Smart TV was bought in 2020 (TCL C815 65") and the manufacturer gave-up on its promise to have upgrades from ATV9 to GTV (Android 11) two years in.

Granted, some firmware updates were available through really alternate/unofficial channels that were published for the Asia and Russia region, but this to say that it had bugs and never really did everything okay (just like lighting control, with really bad PWM). The feeling I have is that this one will some day just plain fail.
And I've got to say, besides 4K resolution and sound being "wow" everything else was underwhelming. Good thing it was at a discount.
Nonetheless, what I want to get to is that many TVs these days are done by brand licensing, the situation being a lot like PSUs from different brands having the same OEM insides. Philips and Sharp, for example, are brands which still give Avg.Joe the perception that they still make their own TVs, but both brands' models are designed and manufactured by TPV and FoxConn (at some point HiSense, China) in Taiwan, respectively. Roku TVs are TCL rebranded models in the US, that I know of. But information about this is not widespread and most TVs do not use components with standards, shared or common parts when it comes to internals, which for decades has been talked about, but makes it near impossible to repair or upgrades for most models.
These OEMs and their supplied displays are many times the main cause for lousy quality and support, but it varies a lot country by country. I remember a time when South America and Saudi LG LCDs would get more features compared to their EU counterparts, so even stuff like "TruMontion" would mean a completely panel and corresponding PSU to support it.