As others have said, it's called salting. It's very gallant and cool.

But, it can take years to get a committee and a authorization vote. Maybe shorter for a local sbux, but you can't just walk in with some red and black flags and say you wanna unionize. It takes time to earn people's trust and time to get them to have faith that unionizing is worth the risk of losing their jobs.

You may not win a union, you may just get better pay and benefits and safety for your fellow workers as a concession and the union effort might dissolve because of it. That's cool to get for your fellow workers but obviously, we have higher aims than pure economism and reformism - we don't want a bigger, "fairer" slice of the pie we want the whole god damn thing and the knife the bourgeoisie used to cut it. It's a big ask for workers without class consciousness but it's possible to develop (and also we need it to overcome the challenges of poverty, war, and climate change as well) and you can be part of that by getting a union in your little local Starbucks for sure.