Jewishfeminist02- It’s not just about trust. How about simple logistics- for instance, if they have little kids, well, kids sometimes poke about where they shouldn’t. Sure, I may trust they’re good parents who teach their children to behave, supervise them etc, but even under the best of circumstances, young kids can be unpredictable and run off and do what they’ve been told not to.
Also, I don’t need people getting a glimpse of how our beds are positioned and other private stuff in our room. It’s not hiding or mistrusting, it’s basic tznius (we don’t let our kids in our room past a certain age). And yes, sometimes it’s a mess and it’s embarrassing. “Just a few minutes” to tidy up my room? Puh-leeze. I’m going through a lot of trouble to keep the common areas plus guest room worthy of your visit- why should I have the extra burden of tidying up my room rather than just locking it?