Yes, because crime is so bad that almost every department, convenience, and grocery store has armed security patrolling outside and guarding the entrance. This isn't a thing in other cities. Even in the south side of Chicago. As a new transplant to SF it seems like shoplifting is actually encouraged here. If I was poor and broke, i would 100% be shoplifting every day. Could probably make a pretty easy 50k a year shoplifting tactically.

Of course not, my point is that there are things the police can do without a conviction, and they do those things in many circumstances. For example, police can famously seize property they believe was involved in a crime.

If it were truly impossible to follow up on someone stealing in broad daylight, that would be the case whether they could secure a conviction or not. If there are officers nearby (as there often are near downtown Walgreens), you might think they would respond once in a while. Presumably they are not, or the staff wouldn't be under the impression that they "don't care".