Animal welfare group PETA wants Starbucks to stop charging customers extra for dairy-free milk in their lattes.

The chain currently charges 70 cents per drink to substitute cow’s milk with vegan options like oat and soy. That policy, PETA argues, is bad for cows and potentially for business.

The group has been advocating for the change since 2019, the same year it became Starbucks shareholder. On Sept. 21, it issued its first shareholder resolution, asking the coffee chain to commission a report on the costs of the vegan milk surcharge to Starbucks’ bottom line.

The resolution comes amid growing demand for alternative milk, from oat to hazelnut. From 2016 to 2021, global sales for milk alternatives grew 23% from $14.4 billion to $17.7 billion, according to data from Euromonitor, a London-based market research firm.

Over that time, plant-based milk has also become a darling of environmental groups. It has a smaller carbon footprint than dairy milk, according to a 2018 study from University of Oxford, and uses a lot less water. But it costs more.

“The products we offer customers in our US stores are priced in line with the broader industry,” Starbucks said in a statement.

PETA is bringing its cause to Starbucks

In August, PETA protestors blockaded the entrance of a Starbucks in Nashville waiving signs demanding the company put an end to it. The organization has enlisted Paul McCartney and James Cromwell in its campaign.

In response, Starbucks has said it pays more for vegan milk than the dairy version. “We expect costs to come down as the supply chain for plant-based options matures and we will pass this onto our customers,” Roz Brewer, Starbucks’ former chief operating officer told PETA activists at a shareholder meeting last year. The coffee chain offers oat, soy, almond, coconut, and a Starbucks-branded nut blend at its stores.

Cow’s milk is cheaper than plant-based alternatives in part due to US government subsidies to the dairy industry. Though the retail price for oat milk has dropped, on average, a half-gallon carton still costs $2.20 more than the same size container of dairy milk, according to IRI, a market research firm.

Major coffee chains are ending the dairy surcharge

Other major coffee chains have done away with milk surcharge. Since 2019, Pret A Manger, the sandwich and coffee shop, has offered plant-based milk at no additional cost. In May, Blue Bottle, an Oakland-based specialty coffee roaster owned by Nestle, started offering oat milk as the default milk option in coffee in all US locations.

And in the UK, Starbucks announced in January that it will no longer charge extra for any of its dairy alternatives in any of its 1,020 stores.

For the PETA resolution to get anywhere, it will need to garner a majority of votes at Starbucks annual shareholder meeting.