Isn't it different though?

Publishing YouTube app on Windows Phone requires Google to put extra effort into developing an app for a completely new platform which I assume requires lot of engineering effort.

Selling Chromecast on Amazon probably does not cost Amazon any extra engineering effort. So, I do not believe that the two situations are equivalent.

Microsoft put out their own YouTube app, no development needed from Google. Google then blocked that app: https://www.theverge.com/2013/8/15/4624706/google-blocks-win...

Sure, since Microsoft didn’t show any ads for google. I think Microsoft might be pissed if google started hosting free copies of their software on their servers.

And allowed downloads, putting Google at billions of dollars in liabilities on their music license agreements.

Funnily enough, MetroTube does both as well and continues to work.

It unquestionably requires engineering effort. And business effort to clear the rights.

It's fairly straightforward as these things go, but to suggest it doesn't require anything is flat out wrong.