It's a warning because the power will be abused. You have 1984 in your username - I recommend re-reading that book if it's been a while since you read it.
I’m appropriately paranoid about abuse of power in other areas, like for example monitoring personal telecom.
One thing to consider is the trend of expected speech or compulsory speech. There are people who would want to see if other people are saying what they want them to say, rather than just not saying what they don't want them to say. There are people who weigh someone's words to see how dedicated they are to a cause or to an idea or to a movement.
These technologies empower language police even in cases where someone would otherwise choose to say nothing. And they establish a precedent.
I am firmly in the “pick your battles” camp.my
Worrying about cameras on the road picking up your speech when 99% of the population willingly carries smartphones doesn’t seem like the right place to pick a fight.