At a recent rally in Hong Kong, protesters smashed the glass front of a Starbucks cafe, dragged some of its chairs into the street and lounged around in them as they watched the demonstration unfold.

It was a targeted attack. Another Starbucks in a nearby shopping complex in the same outlying neighborhood of Tuen Mun was boarded up, its windows shattered. Stores around the two cafes were untouched.

The...