If you have UPVC doors and windows you will, most likely, have catches that (should) engage when you lift the handle. I was surprised, when my house was burgled, to find that there was only one screwdriver jemmy mark on the UPVC. I wondered how that single jemmy could overcome the 5 catches. On investigation of the door, and other doors and windows in the house, I found that the moving bits on the window did not (in many cases) align with the plates on the window frame and so did not function to lock the window or door.
I have wondered since whether this was sheer incompetence on the part of the installers or whether there is a more sinister interpretation. Whatever the cause, you( and anyone buying a new or used house in the future) would all be wise to check your doors and windows .