I know the packets are convenient, and I agree that the seizure of your detergent was unfounded. But there is a simple solution and you don't even have to bother to buy the conveniently sized packages - just pour some of the detergent from your big bottle into an empty 100ml shampoo bottle and mark with an X on the bottom (or something like that) so that you don't mix up your laundry detergent with your shampoo. Or use powdered detergent, which of course will look like a bag of cocaine to TSA.