First off this topic is really not for the NY board but, ok.
Second, there's an old IT adage that says '99% of all computer problems exist between the chair and the keyboard'; the same is true here as smartphone's two biggest players Apple and Android are really stripped down ARM based Unix and Linux Operating Systems at heart.
The post by 'Radio Truth' reads more like a propaganda piece to scare people from other radio mediums than information best served publicly. The truth is TuneIn is an extremely popular mobile application that holds a 4.6 out of 5 star rating on the Google Play Store with thousands of reviews. Everyone's experience will differ but I did want to point out some very false claims he made.
RADIO TRUTH said:
It doesn't even matter if you're not using it, it still drains your cell phone battery.
If this turns out to be the case, you have not properly exited the app and it's running in the background as all platforms support multitasking.
If you uninstall the Tunein radio app, your battery will still drain because the app makes changes to the operating system in your smart phone.
This is a flat out lie. First if you uninstall an app, it's gone, period. Second no standard app installed from iTunes or the Play Store can make operating system changes to your device on its own. Doing so requires administrative or in the Linux world root /superuser access to do so. Even if you managed to have a 'rooted' or customized device (and went out of your way to do this), you are still prompted to grant permission to the system app before anything can happen. Further, TuneIn's app privileges have NO such elevated permission requests so the entire premise is moot.
If you search out this topic on Google, you will see a great number of people who are having significant battery problems with all different types of smart phones with the Tunein radio app. If your battery is draining quickly, here's how to fix the problem. Hit the icon in settings to reset your smart phone to the original factory specs when your smart phone was new. You will have to reenter all of your addresses and phone numbers on some smart phones. You will also have to reinstall all the other apps that you had before you reset the phone to factory specs.
You can Google search for anything you want to, and there's plenty of misinformation to be found. As I previously pointed out, since the app cannot make changes to your operating system, factory resetting is futile and a poor waste of your time. If this turned out to be your personal case, you likely had some other issue with your device that you have mis-labeled the blame for.
As FightingIrish correctly pointed out, maintaining an active cellular connection will drain your battery faster than in Standby, and that applies to all apps, particularly streaming. I typically find a loss of ~7%/hr for radio streaming apps with the screen off, but individual phones will vary. Best advice is to use Wifi where you can as that has less draw than 3/4G, and make sure you properly quit the app when you're done listening. If you're on Android, download GSam Battery (free). It provides advanced battery monitoring with times and percentages so you can keep track of what's really active on your device. Good luck.