"I am not sure that there wasn't a specific reason they started searching there"
(Sorry, I can't bold)
Maybe she was seen walking that way. Just because Pickard hasn't told of any sightings doesn't necessarily mean there hasn't been any. In fact, I think she must have been seen somewhere at some stage that day, either by a camera or a person.
I think you're right. So many places have cameras now. She was parked on a residential street - many people have residential surveillance systems (including CD and MD, which we now know). Coffee shops, public buildings (including libraries), traffic cameras, coffee shops.....