A classic attack on a residential door does not touch the electronics at all: a tool through the peephole reaches the inside handle and opens the door from outside.
How the defence works
The inside handle can be locked in a neutral position, or the electronics can refuse to actuate when the door is armed. Either way, reaching the handle is no longer enough.
Why installers skip it
It adds one setup step during commissioning. Skipped, the function is off and the customer believes the door is protected because the box said so.
How to verify
With the door closed and armed, try to open with the inside handle. If it moves, the function is not enabled.
Where it matters most
Ground-floor apartments, rental units and shopfronts with a peephole on the street side.
Takeaway
The best security feature is one that is actually switched on.