OP, you're right to be very concerned.
There were
56 infections (as of Aug. 26) directly contact-traced to ONE Starbucks over a period of just a few hours on one day. This was in South Korea but the lesson applies everywhere. Here's one article about it, but this was widely covered -- however, not widely enough, or those baristas at your location might have known that wearing masks is vital for workers:
https://www.businessinsider.com/56-got-coronavirus-south-korea-starbucks-mask-wearers-did-not-2020-8?op=1
You can look up other coverage of it.
Having people sitting IN the Starbucks is crazy. The example above shows that these relatively small shops' ventilation systems will absolutely spread the virus to many of those inside if even one person has the virus. You cannot drink or eat with a mask on so anyone sitting inside a coffee shop (or restaurant) is at real risk if just one person inside has the virus and the ventilation blows air over that person and toward others in the room. This isn't "anxiety" or "fear" talking; this is basic science.
OP, please, for everyone's sake including that of the baristas themselves -- report this to whoever is appropriate and complain very vociferously and in writing too, to Starbucks corporate as well as the individual location. ONLY if those of us who take the virus seriously report these lapses, will things even remotely start to change.
To the PP who complained about putting low-wage workers out of jobs: They'll be out of jobs anyway if they get sick enough. And they have huge risk of exposure if they are unmasked or improperly masked and serving crowds of customers. Complaining about the situation OP saw actually helps, not harms, these workers.