Why is it so difficult for competitors to imitate Trader Joe's?

1)Established supermarket companies are not willing to pay their workers like Trader Joe's does.

2)Established competitors are convinced their current operations are superior.

3)Trader Joe's profitability isn't higher than traditional supermarket profitability, so there isn't that much motivation to do so. 4)Traditional supermarkets' commitment to large stores, wide aisles, loyalty card programs, etc. cannot be changed easily.