And it isn't true. There are various things that can be done.
You can shop only at stores that do post prices, even if that means travelling some distance or paying higher prices. You could open your own store and be sure to post prices. You could organize a protest in front of stores that don't post prices. You could form a volunteer service that posts prices for stores.
Obviously, these things require various levels of effort from you. They may or may not be worth it to you.
But "there's nothing really that can be done" usually translates to "there's nothing really I am willing to do."
You can shop only at stores that do post prices, even if that means travelling some distance or paying higher prices. You could open your own store and be sure to post prices. You could organize a protest in front of stores that don't post prices. You could form a volunteer service that posts prices for stores.
Obviously, these things require various levels of effort from you. They may or may not be worth it to you.
But "there's nothing really that can be done" usually translates to "there's nothing really I am willing to do."