[anigbrowl]

Yes, but failure to defend a trade mark can result in the loss of legal rights thereto, even when it's obvious that the infringement doesn't matter.

Suppose they had shrugged this off and done nothing. Then a year later I, a rival grocer, open 'Trader Moe's' and open up 50 stores using a very similar business model to Trader Joe's. TJ sues, and my defense is that 'Pirate Joe's infringed on their mark and they did nothing, so I assumed they had abandoned their rights.

This is an affirmative defense in trademark law, by statute, specifically 15 U.S.C. § 1127 A good summary is at http://www3.ce9.uscourts.gov/jury-instructions/node/248

Unlike copyright and patents, trademark durations are infinite, but the price for this is that the owner must aggressively defend any possible infringement or risk a competitor claiming abandonment.

If you were the Chief Marketing Officer of Trader Joe's and I was the CEO, I'd fire you for not knowing this.