You have to be careful when comparing memory consumption of 'first party' apps compared to third party apps.
Yeah, I also noticed that Safari consumes memory even when it's not loaded because it has some background services running either all of the time or at first invocation. I, personally, set Safari and Chrome to open the same 5 tabs at start, and if you count ALL the Safari processes, it's actually MORE than Chrome. This article is being questioned by others saying the person who tested did not count the 'Safari renderer' processes (which are rather large memory consumers) when counting Safari usage.