There are many barriers that keep humans from fully communicating. Not all can be seen or touched. But in some places -- usually convenience stores and take-out restaurants -- it's plexiglass.

Food, drink, candy and money are passed through holes in inch-thick plexiglass that is often discolored and cloudy with scratches. Some say the bulletproof partitions make patrons feel like criminals and second-class citizens.

In Philadelphia, the City Council passed a measure in December to ban them. The legislation was originally targeted at all stores and restaurants, but a compromise bill focused on so-called beer delis, which critics say exploit poor residents by selling liquor by the shot.

It is unlikely that many of the barriers will be coming down soon. The city’s Department of Licenses and Inspections has until 2021 to announce regulations on the bulletproof barricades.