My parents just ensured the lock on the door knob had a slit on the outside so you could stick anything in there and rotate to unlock it. Half the time, they just used a long fingernail or the edge of a coin. It didn't require much effort.

They'd still get mad at me for locking my bedroom door and would threaten to remove the door if I kept locking it, but it took them maybe 10 seconds to open it without tools.

They never followed through on the threat; I kept my bedroom door all throughout my childhood.