Convenience. Setting up Tailscale is easier than setting up WireGuard by yourself and dynamic dns. Not by much but enough that those who don't know how to do latter might opt for Tailscale
Would be interesting to see the statistics, if someone has calculated them. I wonder if reservists count as combatants or noncombatants. Would skew the numbers a lot
I think people are sometimes taught out of that since it slows down reading