Without going into specifics, I'm a firm believer in the notion that the only people who get a vote in how a relationship works are the people in that relationship.
There are an infinite number of reasons some might choose hierarchical relationships and they're not all about insecurity.
Working on trust issues isn't as simple as deciding you're going to start trusting someone. If they've shown untrustworthy behaviour in the past, then that trust has to be earned back. If you keep stealing coffee money from my desk drawer, I'm going to develop a trust issue sharing an office with you. It doesn't mean I have an innate trust issue about keeping money in my drawer, it means this one specific person has forced my hand. I would be a fool to just keep putting my coffee money in that drawer and come to work every day believing that you're not going to steal it. I could report you, but you're really good at your job and you make mine easier. I don't want you to get fired. So I start locking my drawer.
In other words, trust issues aren't always a matter of the untrusting person being insecure. Sometimes people do things that legitimately make you stop trusting them, and only a moron would ignore that. But maybe you still love that person even though they violate your trust, and you're not willing to throw them out over it. No one's perfect and maybe they're trying to work on their behavioural issues and you've made a commitment to stand beside them and help them through life's difficult times. But you can't do it blindly. So you have to put mechanisms in place to protect yourself against their behaviour. That's not insecurity, it's pragmatism.
“As I am sure any cat owner will be able to tell you,
someone else putting you in a box is entirely different
from getting into a box yourself.” —bisexualbaker