I was in Lisbon a few years ago, and on basically every (major/touristy) street corner there are people trying to sell you drugs

If they spot a tourist, they'll even go so far as to follow you down the street heckling you to buy some

In a legalized country it would be sold by regulated stores, where the supply is known where it originates from (i.e. Head Shops in CA as of the 1st of this year)