[napoleond]

Both you and your parent commenter are sometimes correct, depending on the situation (believe it or not, laws vary from country to country, there are many different types of military groups in each, etc).

Your point of view is not always correct, so it should definitely not be common knowledge.

[gknoy]

The historical nature of soldiers of armed guards with the authority to kill you lends credence to his suggestion that it's not an unreasonable expectation to believe that they _could_ shoot you.

Local mileage and laws may vary, but erring on the side of caution when you see a soldier means that it's prudent to act as if he can legally fire upon you -- even if that assumption is not actually true at that specific time or place.