Ellen and The View are entertainment shows. Second you are assuming the don't incur in any cost to make the videos. They could choose not to make videos about of tragedies, but if they make it the videos still have a cost to produce.
They make enough money from their other videos to not need to monetize videos of children reacting to tragedies, christ.
I agree that the likes of Ellen and The View are entertainment shows. However a huge demographic of people that watch things like The View, Ellen, Tonight Show, the Late Show, etc are tuning in for the little bites of news from the monologues at the start of the show. I don't think a single person on the planet has ever felt the need to load up a Kids React video to get their daily news bites. They watch those videos for entertainment purely.
Also Ellen doesn't go "Hey there was a shooting let's talk to people while a bunch of ads cover the screen." they'll bring on someone affected by the tragedy and interview them and then give them some kind of gift or donation or something. "It really was a horrible tragedy so we're gonna donate $10,000 in your name to the charity of your choice." Did Kids React do anything remotely similar? No, they for whatever fucked up reason thought "Hey, you know what would make a good reaction video? Teens reacting to a school shooting" and then they uploaded it and ticked the box to monetize it.
When Ellen or the hosts of The View talk about a national tragedy they aren't profiting directly off that tragedy, they already have a show with ad time bought and they're gonna talk about whatever is happening that day. The Fine Brothers are. They have to set up and cast and shoot and edit and upload a video specifically of that tragedy. That's the difference and it's disgusting and wrong.