I find it interesting that recreational pot stores are a firearm prohibited place. When the liquor control board ran the liquor stores 21 & under and guns were allowed.
Based on RCW 9.41.300(1)(d) it appears they have the authority to make them prohibited places.
“(d) That portion of an establishment classified by the state liquor control board as off-limits to persons under twenty-one years of age; or”
http://apps.leg.wa.gov/rcw/default.aspx?cite=9.41.300
Pot sales related WAC 314-55-086 states…
“(4) Firearms prohibited signs provided by the board must be posted at the entrance of each producer, processor, and retailer licensed location.”
http://apps.leg.wa.gov/wac/default.aspx?cite=314-55&full=true#314-55-086
I noticed in your linked news story the store that was robbed is a medical store. As they are not run by the liquor control board they presumably do not have any state mandated firearm restrictions. It still shows the risks of running a cash only business selling a desirable product.