I think it's a bit misleading to say Lineage OS sends data, because it doesn't. It's just the GApps installed with Lineage OS that sends data to Google. But you don't need to install GApps, then it doesn't send anything just like /e/OS does...
This is the exact thing I was wondering about. As far as I understood, they flashed GApps, even though GApps is not part of the default installation. I wonder what the findings would've been like on LineageOS without the GApps.