This has come up a few times recently so I thought I would highlight the issue.

Most Mercedes-Benz sedans now have a switch in the glove box to lock the trunk. When this is slid to the locked position the trunk will not open with the key, the handle or the door switch. It is not broken!

The idea is that you can then manually lock the glove box with the blade key, take that with you and now a valet/child/spouse can’t access these areas.

Hope that helps!