If it's walkable, the car drivers have made their choice and can pay for it. If they don't like the price, they can walk instead. Or, use their cars to drive a few more miles to a grocery store with more agreeable parking. There are more than a dozen Trader Joe's in LA, surely one of them has agreeable parking terms. And that's not counting all the other grocery stores in town.
You should look up the specific Trader Joe's the article is talking about on google maps. It's smack in the middle of Hollywood, within walking distance of numerous businesses and tourist attractions. Expecting free parking in that neighborhood is completely unreasonable.