The good news is that most kids don't watch "TV" anymore...The bad news is, its replacement can be even more problematic!
The TV was called the "Boob Tube" back in the day for a reason. It's not new to say that it's addictive, it brainwashes you, and replaces more constructive activities. That discussion isn't needed. However, modern TV has changed into something even worse...streaming.
Streaming is worse than live TV because it further degrades attention span, impulse control, and focusing skills. Way back in the day, there were only a few channels to choose from, so you were stuck dealing with what was on, like it or not. This at least strengthened resilience and learning how to deal with not getting what you want. You also learned how to wait for the show you wanted to see, remember the time, and be there when it's on. This strengthened forward thinking, time management, and responsibility. And now that TV can be streamed on the phone anywhere you are, you don't even need to learn the skill of compromising and collaborating with other people deciding on what to watch.
Another benefit to having only a few channels is that more people were all watching the same thing. This resulted in greater social connecting, as we were probably all talking with each other about the same show the next day. When there was only one TV in the living room, all the viewers were watching together, sparking group discussions and analysis of the problem solving and moral decisions that the characters being watched were making. That's all gone now.
It's essential to let your kids know that TV is entertainment. Tell them that just because the TV acts like something is a certain way, doesn't mean that it really is. However, even though the news bases its programming on whatever gets good ratings, if the news says that there is a hurricane coming, don't ignore it!
Although the potential damage of TV has increased, the response is still just the same...Moderation. TV time should be limited to no more than 3 hours a day.
"How can I control how much time my kid spends watching TV?"
The most practical way of limiting TV time is using an app which is made to do just that. I know it sounds like jail, but if they are raised from the start with a timed TV period, they will accept it as normal. You can also use extra TV as a reward for positive behavior, and take away TV time as a consequence for negative behavior.
Some people say not to have a TV in their bedroom, but I'm OK with that. If they are in their room it's downtime anyway. I'm also OK with having the TV on in the background while they are doing something else. And if what they are watching is providing some level of emotional or educational growth, then that's what it was originally intended for.
Summary
The option to watch any show you want, any time you want, anywhere you want, may sound like a good thing. However, it breaks down learning basic life skills and increases the already inherent addiction of TV.
Making TV easier...makes living "real life" harder.