Question reg "clean" vs "unclean" ac

Hi!

This is a question to all you out there flying between commercial fields and
uncontrolled private strips.

In Europe these days, there is some legislation coming reg access to
airports, and security.

Basically, it involves that any person inside the fence should be "clean" in
other words go through a scanner and security check before allowed out to
the ramp.
Which makes sense.

However, what happenes when a C172 flies from a grass strip, and lands on
tha capital's international airport.

No one has "scanned" him at the grass strip, and thus he is not "clean". He
could be carrying a s***load of explosives on board and tax over to the
commercial planes, right?
Doeas he have to stop at the taxiway and be "checked" out by security before
taxiing to the hangar?

Do you have any rules for these sort of things in the US or other parts?

how about flying clubs operating from commercial airports? Do you have to go
through a security check every time to access the C150?

Anywere on the net I can learn more about these things in different
countries?

Thanks,

Frode Berg
Norway