Cashless stadium transactions may be convenient for spectators, but the concept doesn't have many fans among concessions vendors.

Six out of seven Mercedes-Benz Stadium vendors interviewed by Forbes said they are disappointed in the tips under the Atlanta venue's credit-card-only policy implemented this season. One vendor selling beer and water to patrons on the stadium's the 200-level concourse bemoaned a two-to-three-week delay for tips from sales made on a credit card machine worn around the vendor's neck.

Another vendor told Forbes that because the tips are taxed, they are lower than what could be counted on from cash exchanges. Tips are part of the U.S. underground economy of more than $2 trillion, and many tips are not reported as taxable income — a widespread but illegal practice.

Related: Mercedes-Benz Stadium to Be First to Go Cashless

As reported by Forbes, a vendor behind one of the popular beer/wine/liquor gardens overlooking the field said tips were good. Fans leaning elbows on the bar as opposed to walking the concourse to order a drink will push the “tip” button on the machine. “I’m doing better,” the bartender said. “I can look at my tips after every game and see I’m doing better.”

Conversely, a different vendor behind a simple beer station said tips have been disappointing. “It is not better,” the vendor said. “People swipe the card and run off before doing the tip. I thought it would be better this season, but it’s not. It’s about the same as last.”

“Worse,” said a vendor behind another station. “Thanks for asking me. People don’t have cash and they don’t push the tip option.”

Mercedes-Benz Stadium, notable for its atypically low stadium food and beverage prices at Atlanta Falcons and Atlanta United games, appears to have placed a gag order on vendors when it comes to discussing their actual pay in the media. Vendors did reveal that they are not allowed to display tip jars. Fans with cash are required to convert to cards using machines inside the stadium.

Mercedes-Benz Stadium did not respond to Forbes' email request for comment.

Paul Steinbach is Senior Editor of Athletic Business.