What? My experience was the complete opposite of yours. Not a single tech person I interacted with even batted an eye if someone said they worked at Google, most of the time you will just get "nice, what team?" When talking to non-tech people, a lot of them tend to think that everyone working at Google is a super genius changing the world.

EVERY tech article about the hot new startup introduces the founders in the following way. If they previously worked at Google, Facebook, they mentioned it. They don't say "founders previously worked at Google therefore THEY'RE AMAZING". But they mention it. If they previously worked at an irrelevant company, they don't mention the company. What's implicit is that if you worked at Google that's remarkable and worth mentioning.

That is prestige by association. If you can't see it.... well, I just hope it's not because you're in denial.

EDIT: Also, VCs. It's a lot easier to get a VCs attention, or a recruiter's attention, if you say you previously worked at Google. If any of this is news to you, I don't know what else to tell you...