Why are the minima for Cat A higher than for other categories at KSEA ILS 16L?
The minima's are usually decided based on the Missed Approach procedure, which one of the criteria being obstacle clearance. I believe the answer lies in your question, its due to the heading course and altitude restriction on the MAP point. RWY 16L needs to climb straight 165 deg which puts you through the obstacle , whereas 16R Missed approach procedure heading can clear the '464' obstacle. . In either case Obstacle driving the change, Having CAT A with the lower speed in the heading of 165 deg it won't get you clear the obstacle. The PBN approaches are even marked higher for all aircraft type which can be inferred from other terminal charts.