A quick search determined that at least in Switzerland and South Korea, there is an avenue for conscientious objection, so I wouldn't say that "military service" is mandatory there. Even in Israel there seem to be plenty of options to get around military service.

I recommend the Wikipedia articles about "Conscription in <insert country here>".

There are four relevant categories:

a) People conscripted to serve in the military.

b) People who choose civilian service to avoid military service.

c) Conscientious objectors who go to prison instead of serving.

d) People who could be conscripted but somehow manage to avoid serving.

From my Finnish perspective, "mandatory military service" means that the ratio (a + b + c) / d is high. Civilian service does not exist because the country wants to use slave labor instead of paid labor, but because it's socially more acceptable than imprisoning people who refuse to serve in the military.

In both South Korea and Switzerland you’d still be required to do civilian service in lieu of military service.

True, that wouldn't be "compulsory military service" though imo.

It is compulsory, but with exceptions. Defining something by the outliers just messes with the language of things :)

"The exception that proves the rule"

In this example though, it would be like arguing the taxes are optional. :)