I witnessed shoplifting done several times in Citi Center.

There was one time the alarm went off in NEXT but the lady ignored it, continued walking and motioned her maid to push fast her Carrefour pushcart. The saleslady was unable to do anything.
I also saw a similar thing happen in Debenhams but the poor male guard could not do anything to stop the two ladies. They just turned to him and motioned not to touch them or their bags. He called the store manager but they were unable to identify the two ladies who walked off into the crowd.
Most of the things taken are small items or shirts. In Carrefour or most groceries, it is consuming drinks, chocolates, bread, etc. without paying for them and then leaving the cans, bottles and wrappers on the shelves.

If you do not see shoplifting happening here in Qatar then I think you choose to ignore it or you are blind.