I guess you are right, it's apple vs. oranges. If we take GKE out of the picture, in terms of setup, is it accurate to say it competes with Kops?
Kops seem (from quick overview) to be focused on AWS and/or other cloud providers. Several times I've been limited either to actual hardware in a room, or a contracted provider giving me something along the lines of OpenStack. Unless there's a project I've missed, at the moment that means I either have to deal with kubeadm, or just roll from scratch myself (umm... nope).
Yes, true, but that's apple vs oranges. Swarm doesn't compete against GKE, it competes against Kubeadm. Because sometimes one actually can't or won't use cloud services.