We live in a golden age of brand activism: multinational corporations no longer want to simply flog you stuff, they want to lecture you about social justice at the same time. Take Uber, for example. The ride-sharing company, which conquered large swathes of the world by flouting regulations and classifying its drivers as contractors so it doesn’t need to give them benefits or the minimum wage, has taken a bold stand against racism in a new ad campaign. “If you tolerate racism, delete Uber” billboards across the US proclaim. The campaign launched on 28 August, to coincide with the anniversary of Martin Luther King Jr’s “I Have a Dream” speech. I’m sure Dr King is looking down from heaven with tears in his eyes, giving Uber a five-star rating.

I don’t want to slam these ads entirely. Cynicism aside, it’s a good thing when big brands take an unequivocal stand against racism; it’s a sign of progress. And Uber isn’t just putting up billboards, it has also pledged money to support black-owned business and committed to ridding its platform of racism.

But while Uber has made lots of promises, it’s hard to get around the inconvenient fact that its entire business model is fundamentally exploitative. Uber is practically synonymous with the “gig economy”, which has decimated labour laws under the guise of “flexibility” and which is disproportionately staffed by people of colour: according to one study black workers are twice as likely to be on zero-hours contracts compared with their white peers.

Uber has also fought tooth and nail against attempts to reclassify its drivers as employees and pay them the national living wage. But even that’s not enough to make the company profitable: Uber’s long-term future rests on replacing its drivers with self-driving technology; such automation could make racial inequality even worse. So enough with the woke-washing and sanctimonious apptivism, Uber. We don’t want slogans, we want substance.

• Arwa Mahdawi is a Guardian columnist