Good point! Sadly, I don't have access to the Harvard study (https://pubsonline.informs.org/doi/10.1287/mksc.2019.1200), so maybe someone with access to it could check it, but the linked article might be misleading in some aspects (depending on the results of the study shown in the paper).

From the study's abstract:

> A preregistered field experiment indicated that diners were 21.1% more likely to buy a bowl of chicken noodle soup when a sign revealing its ingredients also included the cafeteria’s costs to make it.

From the linked article's sub-title:

> Sales of a chicken noodle soup increased 21.1% when people were shown the costs of making it.

The study's abstract mentions that they were more likely to buy a bowl of chicken; it's not mentioned that they actually bought it.