The obvious problem to this armchair expert "solution" is that Google doesn't know what I am already paying. I pay NYT for a subscription, but Google doesn't know that. For obvious privacy reasons users don't want to tell Google what sites they already have subscriptions with. And I don't even log in to Google to do a search so there's no place to store that information even if I actively wanted to provide that to Google.
I wasn't presenting it as a perfect solution. I was observing that many people don't want to see paywalled results, some may want to see all of them because they may choose to pay, some may want to see them because they plan to use a paywall bypass, and some as you pointed out may want to see the subset they already pay for but not others. As a first pass, a binary approach seems better than nothing, and is simpler to provide than a more complex user-subscription-specific solution.