The coordination is incredible. It's been easier to ban kids from social media (and impose id verification at the same time) than it was to ban landmines.

It's not surprising at all. Kids in soveriegn nations are banned from all sorts of things. There is no governing body over sovereign nations that can simply ban land mines. You're talking about countries promising to reduce a common war power.The Ottawa Treaty is a treaty (ie mutually agreed upon rules which can be exited) and not all countries have signed it.