I trust Mozilla to do the right things… in general. I trust so much that I agree to share Firefox telemetry data to its server. I trust Mozilla to hold my traffic data, bookmarks etc with Sync. The thing is that I remember being informed of those options the first time I start Firefox on a new machine. Trusting Mozilla and Firefox is a choice I make, even if it’s the default one.
I didn’t like waking up and reading that Mozilla partnered with a TV show and silently installed an add-on on my computer. I don’t care what that add-on does: Mozilla sneaked it in on my computer. I don’t remember seeing any notification upon restarting Firefox, like “Hey, we partnered with XYZ Corp to collect anonymous data and do something great with it” or “Sorry, we just need to make money… It’s all good, we keep everything private as usual and no marketing bozos will bother you… Do you mind not changing the default and let this add-on run?”