system
Given the following post, respond as if you're commenting on Reddit:
human
Why do remote controls still rely mostly on infrared technology, not radio?

Subquestion: is IR technology really cheaper than radio wave technology? It would seem so. But it also seems that radio transmitting/receiving technology costs next to nothing. One can buy FM transmitters for about 1 Euro in a thrift store. Cheap portable FM receivers cost about the same.

I know that Sony uses it in some of their more expensive devices. Why is it not used universally by some cheap brands?
gpt
While yes it is better because the signal from a radio can go through things, this can also be an issue. Imagine if you had two rooms side by side with the same make of TV, the remove would control both TVs at a time instead of just doing the single one.

Yes you could remove this by pairing the TV with the remote, but why not just keep using infared if it works, and doesn't have any serious limitations?