In an ideal world, no country would even have a reason to have universal conscription. We do not live in an ideal world, though, we live in the era of dying imperialism, where the US Empire could lash out at any moment. In these circumstances, the decision to implement universal conscription is entitely rational. Further, I am not purely speaking of children, but also full adults getting their medical degrees and having to give back to the system by going to the areas most in need for a time.
As for democracy, the book I linked is the best source I’ve found.









You may oppose it, but you also likely do not live in a socialist country. Understanding why socialist countries have the policies they do requires understanding their situations. For example, in Cuba, sending doctors to the rural areas helped provide medical access to people who never had it before. These programs are not at all comparable to slavery, but are pro-social policies decided within a class, not imposed by one class onto the rest.