It's a few pennies cheaper and i'm sure they have some data showing 70%+ will just use WiFi. TCL in particular doesn't even have very good/stable drivers for their 10/100 NIC; there's a ton of people on the Home Assistant forums that have noticed that their android powered smart TV will just ... stop working / responding on the network until it's rebooted.

It's not that bizarre. About the only media one might have access to that is above 100mbps is 4k blu-ray rips which can hit peaks above 100m; but TVs don't really cater to that. They're really trying to be your conduit to commercial streaming services which do not encode at that high of a bitrate (and even if they did, would gracefully degrade to 100Mbps). And then you can save on transformers for the two pairs that are unused for 100base-tx.