To be honest, I think your question is a bit silly. The government can do whatever it wants with seized assets. It usually auctions them off because the money is more useful than the assets. In other words, if it seizes trucks, real estate and tools, for example, it is more useful to sell them and use the money than to keep the assets. They also often seize cash, which they do not auction off. Have you ever thought about that?

So, if a certain type of asset is more useful to keep than to auction, it's normal for them to do so.