Some places do take it more seriously. Philadelphia has long been lax with enforcing laws and prosecution. The events of 2020 further encouraged more brazen lawbreaking. Many realize the police won't do much. Heck, even if the crime is on camera, takes place in broad daylight, and in front of witnesses they'll likely still get away with it.

As for why scrap yards aren't more scrutinized deserves more investigation. Do various scrap yard owners have strong political connections? Too costly / time consuming to enforce metal theft? Or apathy? Often one hears the authorities say "insurance will cover it". Often it only covers some of the loss at best. Basically, an excuse for the authorities to ignore most property crime. It's appalling.