It is up to the police to give a pass for ignorance of the seat-belt law and provide warnings.

That said, I don't understand why someone wouldn't -- even in the absence of fines -- automatically default to using a seat-belt when getting into a car equipped with such safety restraints, whether at home or abroad, especially if already routinely using such devices when in one's own home area. I certainly don't understand why someone with the means to pay such a small fine for such a legal infraction would consider not paying the fine even if it's unlikely for the person to return to the fine-issuing jurisdiction for a long time.