Even with an honest company, the pressures on them are twofold – security and legal. Their systems can be compromised through security vulnerabilities and social engineering (including coercion – money, ideology, compromise, ego – classic psyops playbook). Or they can get legal government orders - which pretty much every government in the world have laws on books and operational practices to force any actor to hand-over data in the name of fighting money laundering and terrorism (AML/CFT). It is very expensive to put up strong defenses against these. I don't see a viable business model charging $5/month that covers regular operational expenses and covers these types of events.

Edit: Forgot to mention backdoors built into basic technologies they may already be using – like the Cavium HSM thing that came to light earlier this week.