One thing to remember is that most items in the Sixth World have some level of electronics, and are considered "owned". Even those art pieces may have an RFID tag in the frame that is the equivalent of a certificate of authenticity (without which they would probably be considered forgeries). This prevents a lot of casual looting, as it is not a simple process to change ownership.
Now, if the owner is cooperative, changing ownership can be done in about a minute. Presumably, if the owner is under duress, there's a process for reporting the theft after the fact, either by the owner or someone else (such as the corp that finds dead guards with weapons and comlinks missing). So, be careful about intimidating someone into giving you their stuff. The more practical option is switching ownership, which requires an Extended Hardware + Logic [Mental] (24, 1 hour) test, and the item must be on the Matrix during that time. Granted, the item won't raise the alarm unless you glitch...but if the owner gets on the Matrix in the meantime, they can track the item and alert the authorities. Unless the adventure has a lot of downtime between scenes, you'll have to do this between adventures - which means you need at least 15 dice to buy the necessary hits. To my knowledge, there isn't anything to give you bonus dice for this type of test, so this is very hard to do. I never let characters just take equipment off fallen foes as their own, unless the item in question is a throwback with no electronics.
Now, if a character spent the effort to get their Hardware and Logic high enough to make the extended test, AND the item isn't hot enough that tactical teams will be sent out as soon as it pops on the Matrix, then sure, let them reap the rewards. I generally go off the guidelines for what players can give to each other - up to 5k of items in an adventure is fine. More than that, and you better have a solid plan for how you're going to switch ownership before the original owner (or their corporate overlords) catch up to you.