This isn’t about “depriving people of their freedom”

No, but depriving people of their freedom is what conscription does. It can be necessary, just as depriving people of their money via taxation is necessary, but you should be honest about what you're doing.

Nobody can expect others to defend them if they won’t do the same. An integral part of the social contract in countries with conscription is that everyone accepts that duty to answer when called upon, and to defend their countrymen when necessary.

Yeah, but you're using the opposite of the solidarity principle here. As I said, it's reasonable to use conscription if you actually need a lot of people. I very much see the point in what South Korea or Israel are doing with conscription (albeit that they're a bit sexist with it). But if 98% of the birth year cohort (and 99.98% of the entire population) get to enjoy their freedom while a tiny minority is forced to join the army, then that's a serious injustice. Imagine doing taxation that way. Next time the state needs more income: Don't raise income tax by 1% for everyone, just you could pick 1% of the population and raise it by 100% for them.

As long as the army doesn't need (almost) everyone to have served, incentives paid for by everyone should be used to get enough volunteers.