First, sorry if this is a topic that keeps coming up, and i am accidentally repetitive.

In a World War movie that involves escape and evasion, they often involve getting past the border of Switzerland. Sometimes its Spain, but i get that would be less common since the time after D-Day that German holdings bordered Spain was short and that Spain while neutral leaned closer to diplomatically favoring the Axis.

Anyway, it seems really crazy that everyone on both sides universally agreed to an "out of bounds zone" where if entered you can say "olly olly oxen free" and be exempt from being shot or captured.

What makes it more surreal is that it is a landlocked country directly between Italy and Germany. When the Axis is setting out to control as much of the world's land as possible, how does such a nearby and small country manage to convince them that they should have an exempt status?

I'm sure Belgium or Luxembourg would have been keen on a deal where: no invasion happens and everyone else has to move around them to fight the war because "thems the rules", but it doesn't seem like such an option was available to them. Why not?

Furthermore as an aside curiosity, since Switzerland is landlocked and very hilly, how would the logistics of escaped POWs getting back to their own country work? Surely, the neutrality would also be preventing military aircraft from using their airports. Were there civilian commercial flights still going in and out during the war, and if so: really? Like, during WWII, you could just walk up to the ticket counter and book a flight there?