Your entitled to your own methods of living life, but I feel like giving your children "no privacy" is a bit of an extreme approach. Have an open conversation with your children - let them know the expectations and the consequences of not adhering to those expectations because instead of actually communicating with your children, it sounds like you stalk them instead to manipulate them emotionally. Were your phone calls and private conversations monitored as a kid/young adult? Not allowing children to have a safe private place where they can just chat to their friends can be emotionally cramping. I'm not sure how old your children are, they could be 6 and 8 y.o for all I know, but rummaging through their things either in real life or digitally can cause a lot of problems later on if they are older. It also depends on the approach. Do they get in trouble if they're talking to someone from school you don't approve of? Do they get in trouble if they vent about how they don't like one of the other girls at school and don't want to sit with her anymore? Do they get in trouble if they're "dating" someone?
Not allowing your kids to have any privacy isn't something your children will “understand” later; you may not be forgiven, you will not be confided in. You will create trust issues for your children for their future relationships. As you said yourself there's private things you don't even want your own children to see. Private conversations about *them*. What is there to hide? Nothing? You probably just don't want people going through your personal stuff and have someone call you out and analyse everything you do. It's the same for anyone. Even kids.
If you violate your child's privacy in this way you'll never earn their trust, you're just creating a better liar. If they get in trouble for texting someone - they'll just delete the texts from that person so you don't see them. If they get in trouble for calling someone you don't approve of - they'll just use their friends phone to make the call next time.