Let's say you decided to make every airline display how much it costs to fly with one checked bag... well, why did you pick one? What if one airline let's you check two bags free? Or if one gives you free food but the other charges? Has more leg room? Etc...
Pricing transparency laws only help things like "you have to include all taxes and fees for the exact item you are selling"
It doesn't help with requiring a company to include certain extras (like a checked bag or two) with the price. You are allowed to choose how you bundle things together, no matter the pricing transparency laws.