Both WSJ and NYT (maybe also other publications with a paywall) will display articles if you are coming from Google. Just entering the article title (article URL tends to work, too) into Google will get you there without any paywall. (I guess this is also why looking at the cache works.)

It’s a form price differentiation, really. Also, I’m guessing this is probably the reason why many are not aware of the paywall and link to these articles.

In this case alternative and equally good sources without paywall exist so it doesn’t make much sense to link to the article with paywall (but that might have been a mistake). However, I do not understand objections to paywalls in principle.