The first is an easily solvable problem - Levis Corp could create a registry of verified vendors, which customers could check before buying.
The second one is the problem the law is trying to solve. People often buy a bag with a G written on it that they know doesn't come from Gucci. They get the status benefit of Gucci without actually paying $1000/bag.
I.e., it's basically a back door way of bringing back sumptuary laws: it's illegal to display status unless you have status.