[bhnmmhmd]

> If their phones were perfectly secure there would be no debate if they are willing unlock the phone for any agency or not.

Total security is not possible, not at least by a long shot.

Although, I understand your concern about why people trust these companies. While I don't know the answer just yet, I think one reason is that most these companies are located in Western countries where "rule of law" is considered extremely crucial. Openness about balance-sheets, government policies, and privacy are - to the best of my knowledge - critical in the US.