If you say you know for certain, it makes sense to ask how. It makes a big difference if the answer is “I used to work there”, or “I implemented those systems myself”, or “I heard my cousin’s second ex-wife say she heard it from her hairdresser”, or “aliens visited me in my dreams and told me”.

I don’t doubt these companies are lying through their teeth. We have plenty of proof of several cases where they did, to the point believing they are liars is a sensible default, but still I could not say I know for certain of every instance of their lies. Knowing how empowers you to do something about it and convince others.