Bounties accelerate games - A misunderstanding? ((MINOR SPOILERS FOR LEC))

At the time of writing, OG's Zoe (Nukeduck) has 160-170g over her opposing laner Ryze. The team gold difference is almost identical, 700g apart in total, amongst all 5 champions, at 20 minutes. (Thats a 140g average advantage, or 175g if you discount supports)

And yet she has a 300g bounty, just under double the gold difference she has over Ryze and just over the gold average advantage. Killing Zoe once, alone, would bring the entire G2 team to Origen's total team gold. That's not "anti-snowball" or "comeback mechanics", that's how you START a snowball. But I'm not here to complain, I'm asking if I understand the bounty system correctly and what it's tracking - Obviously the exact data is confidential, but like many a reddit posters and ADCs on boards, I don't know why the bounty is so high when the difference is barely a minion wave.