Random sims walking through house/apartment

I didn't see it happen, but I left a cowplant berry on the ground inside a fenced area with all gates locked for everyone except household, and came back to find the cowplant berry had been planted. Gate and door locks really need some work. Currently there's no way to check a gate's locking status - who is or is not allowed through - and a number of times I've applied two different lock settings to a gate and the second one has deactivated the first lock setting. The whole system needs a re-write. But in my current household, "lock for everyone except household" is the only setting I need because they don't have infants or poultry to contain, and it just simply didn't work.