Not only is it manipulated, it's flagrantly obvious. PewDiePie for example trends in many countries except the US [e.g. 45 times in Canada, 42 times in Germany vs 1 time in the US], and it's not just him either but many "controversial" channels.

Source: an analysis of 40,000 trending videos [7 months of trending tab videos]: https://www.youtube.com/watch?v=fDqBeXJ8Zx8