Is lack of 4K content because of the tech or its out there?

I noticed that VOD section for movies can be decent for 4K, but when it comes to TV streams its non existent. at Most you will get a few foreign channels.

Is this because the tech isn't there yet to stream 4K content live, or are there just no 4k channels. Sorry I haven't had cable in 20 years so I don't know if there are 4K abc's and NBC's etc.... Especially sports like ESPN and TSN.

So is it because the streams don't exist or is it because its just to much bandwidth? If we can stream 4K VOD why not live?