Don't understand the OP's point. It doesn't do any good to pad the schedule for ATC delays, because on the days when there are no delays, the plane will just arrive 45 minutes early and sit waiting on the tarmac for a gate at SEA. Also, they tend to load up and wait because there is a chance they will receive an earlier takeoff clearance. They have to pay the pilots based on block times, so adding in unnecessary padding based on the chance of delays is costly. Best option is to not book a 40 min connection in SEA because there is a good chance of missing it if any ATC delays are in effect.