The notice is so you can make a plan to let them in.
If, for example, the unit below yours has water coming through the ceiling I don't know of anywhere that requires them to give you 24-48 hours notice.
Check your lease; YMMV; most people aren't actually allowed to tamper with their door locks. Shocker, I know, right? When the Constable comes to evict you, your landlord/owner's going to have the keys to let him in.