Namely : Arizona, California, Connecticut, Delaware, Hawaii, Indiana, Massachusetts, Michigan, Minnesota, New York, Texas, & Vermont have laws that ban requiring memberships for the purchase of alcohol.
IIRC, Costco's lobbiests played a large role in Washington's privatization of liquor sales, and the final law did not include such a restriction.
For those interested, the break even on a 2% cash back membership is at the $2k/year.