[jotux]

Yes all physical security can be defeated but you could make it exceptionally difficult to do. As an example, I used to work on financial terminals and sat across the isle from one of the security engineers. They actually embedded conductors in the case that created a known EM field when the case was closed. If you opened the case, it disturbed the field and erases the keys. If you drill a hole in the case, it disturbs the field. If you melt the case and insert a metallic object (screw driver or knife) it disturbs the field. This was just one of the physical security measures.

tl;dr - modern physical security is much more than microswitches.

[Eridrus]

Do these systems still hold up when an attacker has practically unlimited physical access to the device and you do not?

This seems like a very challenging environment for tamper detection.

[amatus]

I'd like to see that stand up to mom vacuuming right next to the unit.