How are so many people being charged without their knowledge or authorization?
Not reading properly what is on their screen when ordering is the most common cause.
It depends on the country but in most ones automatic renewal (aka continues protection) is enabled by default.
If people don't uncheck it, they they shouldn't say the have never given permission because they did gave permission for it.
Fact is that if automatic renewal is enabled, people will be charge around the time their subscription ends.
It also happens that someone else in the household has ordered avast and forgot to tell the other(s) about it.
how did you get my checking account info and why are you charging me for this?
I don't have your info as I do not work avast nor any of the payment processors they are using.
But it is real easy, you or someone else gave it to them.
As far as I know they are not clairvoyance or something like that.
avast nor any of the payment processors they are using is scam.
If you believe otherwise, go to the police and report it but don't look surprised if they say that you filed a false report.