I believe the deeper meaning is that even while weed is legalized in several states in the US, there are still many people in those same states serving sentences over the drug when it was criminalized. Those sentences were absurdly harsh, and disproportionately targeted black people.

So when the girl in the painting sees the dispensary, which is supposed to be a symbol of progress towards legalization, she instead sees her dad—still in prison, trapped from behind the glass in one of those restricted visitation rooms where you can only talk to one another over inline telephones.