In Washington state, most dispensaries make you give them a copy of your state issued ID and your medical recommendation/card. This puts the patient in a precarious situation, having to decide if it's safer to buy meds from drug dealers or from retail locations which can get busted and send your info to the feds.

Do the farmers markets also require this?
Do all retail shops?

Seems that if liquor stores and pharmacies can give you drugs/medication with a visual verification then there would be no problem with doing it the same way for medical marijuana, but I haven't seen any written law either way.