The important and very real distinction is the change from per-hour to per-second. If you're going to make it more granular (which from per-hour is a good thing), why would AWS stop at per-minute if it's the same or only marginally more difficult to make it per-second, particularly when they have the added benefit of being more granular that GCP? In other words, I don't see the reduction as primarily a marketing move on AWS's part. I'm sure they felt pressure to make it more granular. Stopping at parity doesn't necessarily make sense, nor should they be called out for doing more purely for marketing reasons.