Pot's illegal at the federal level, so major banks won't provide services. Therefore, vendors can't accept credit or debit cards.
Legalization advocates say there is a tax, and business case, to be made for federal legalization.
Harris said a Biden administration would decriminalize marijuana and expunge the records of people convicted of marijuana-related offenses.
Pot retailers are open for business in most states where recreational sales are legal.
Publicly traded cannabis companies have proven a risky investment play.