The wake from a mega multi ton airliner is a lot more powerful and far larger than the wake from a goose's wingtip. Also the following planes are not following in that "sweet spot" just off and behind the wingtip. Instead they are flying into the disrupted vortex zone many seconds or minutes afterwards when it's had lots of time for the two formations to grow, slightly dissapate but more importantly collide and churn around from that collision. Suddenly instead of riding the wave like a surfer you're being dumped into an oscillating washing machine. So it's two totally different situations.