Because it's business and the dollar rules. If you made a rule about price-fixing water they would just add something to the water to not make it officially water. Then sell it for $10.
They do this in China, Russia, heck the Sahara. Businessmen will find a way to get an edge, always. The only thing we can do is educate ourselves to not be suckered and boycott bad behavior by simply NOT buying.
IE: BUY LOCAL HONEY
Anything on the shelf that says 100% honey is not 100% honey. The FDA cannot determine if a batch of 100% honey is actually what it says it is without expensive testing. So they just cut corners on regulating it. A
not-so-recent article on this says that as much as 3/4 of the honey on your shelves is not 100% honey. In fact, manufacturers can fool simple tests by just adding a minimal amount of 100% honey to a larger mixture of Corn Syrup/Beet Sugar/etc. and get away with it. A local honey manufacturer here in Del Rio, TN. Has been caught backing up tanker trucks of corn syrup to its processing facility and STILL selling their bottles labeled 100% Mountain Honey.
Honey is very good for you IF it is local. The local flora is what affects your body, so you need honey made from that local flora. Buying honey from Pennsylvania when you live in California wont help you. Buying honey that is superheated in manufacturing processes kills most of what's good about honey, it won't help you. Your only source for honey should be your local farmers market where you can buy from a TRUSTED source so you know your getting 100% local honey.
Businesses serve their board of directors and have a bottom line to make a profit. They will cut corners, fudge records, and straight out lie to do this. Until human nature changes, our way of doing business will not. We can regulate them with all the bureaucracy we can muster, but there will always be loopholes and lobbies to create them that allow for profits to be poured through.
YES, we should have checks and balances. But that will only be able to do so much.
The best course for any consumer is to vote with their wallet.