Largely because there are many people who are suspicious about GMO's and want to know if they're buying them
Any consumer who wishes to know whether or not a food has been genetically modified by rDNA techniques already has that information. Anyone whose suspicions induce him/her to eat only foods that have not been genetically modified by rDNA techniques already knows to buy foods voluntarily labeled "organic".
and if we operate on the basic capitalistic principle of "buyer beware", they should have a right to know that which they want to know.
Have you read what has been posted on this thread at all? See
International Dairy v. Amstoy in #66. The government does not have the power to compel persons (including businesses) to speak in the absence of a substantial governmental interest:
We do not doubt that Vermont's asserted interest, the demand of its citizenry for such information, is genuine; reluctantly, however, we conclude that it is inadequate. We are aware of no case in which consumer interest alone was sufficient to justify requiring a product's manufacturers to publish the functional equivalent of a warning about a production method that has no discernable impact on a final product. See, e.g., Ibanez, 512 U.S. at ----, 114 S.Ct. at 2090 (invalidating state requirement that Certified Financial Planner (“CFP”) disclose in advertisement that CFP status was conferred by unofficial private organization despite unsubstantiated claim that public might otherwise be misled by CFP's advertisement). Cf. Riley, 487 U.S. at 797-98, 108 S.Ct. at 2677-78 (holding unconstitutional state requirement that professional fundraisers disclose to prospective donors factual information concerning the percentage of contributions actually passed on to charities notwithstanding the fact that prospective donors might find the truthful information relevant and persuasive).
Although the Court is sympathetic to the Vermont consumers who wish to know which products may derive from rBST-treated herds, their desire is insufficient to permit the State of Vermont to compel the dairy manufacturers to speak against their will. Were consumer interest alone sufficient, there is no end to the information that states could require manufacturers to disclose about their production methods. For instance, with respect to cattle, consumers might reasonably evince an interest in knowing which grains herds were fed, with which medicines they were treated, or the age at which they were slaughtered. Absent, however, some indication that this information bears on a reasonable concern for human health or safety or some other sufficiently substantial governmental concern, the manufacturers cannot be compelled to disclose it. Instead, those consumers interested in such information should exercise the power of their purses by buying products from manufacturers who voluntarily reveal it.
Accordingly, we hold that consumer curiosity alone is not a strong enough state interest to sustain the compulsion of even an accurate, factual statement, see Riley, 487 U.S. at 797-98, 108 S.Ct. at 2677-78 (compelled disclosure of “fact” is no more acceptable than compelled disclosure of opinion), in a commercial context. See,e.g., United States v. Sullivan, 332 U.S. 689, 693, 68 S.Ct. 331, 334, 92 L.Ed. 297 (1948) (upholding federal law requiring warning labels on “harmful foods, drugs and cosmetics”) (emphasis added); see also Zauderer, 471 U.S. at 651, 105 S.Ct. at 2282 (disclosure requirements are permissible “as long as [they] are reasonably related to the State's interest in preventing deception of consumers.”); In re R.M.J., 455 U.S. 191, 201, 102 S.Ct. 929, 936, 71 L.Ed.2d 64 (1982) (“warning or disclaimer might be appropriately required ․ in order to dissipate the possibility of consumer confusion or deception.”); Bates v. State Bar of Arizona, 433 U.S. 350, 384, 97 S.Ct. 2691, 2709, 53 L.Ed.2d 810 (1977) (state bar association could not ban advertising that was neither misleading nor deceptive); Virginia State Bd. of Pharmacy v. Virginia Citizens Consumer Council, Inc., 425 U.S. 748, 771-72, 96 S.Ct. 1817, 1830-31, 48 L.Ed.2d 346 (1975) (regulation aimed at preventing deceptive or misleading commercial speech would be permissible). Because Vermont has demonstrated no cognizable harms, see Edenfield, 507 U.S. at 770-71, 113 S.Ct. at 1800, its statute is likely to be held unconstitutional.
http://caselaw.findlaw.com/us-2nd-circuit/1210635.html
The fact that lots of people tenaciously hold irrational ideas and beliefs about the dangers of GM foods--despite the extensive and conclusive evidence that GM foods pose no greater risk(and actually less risk) than foods whose genomes have been modified by conventionally breeding, hybridization and radiation techniques--does not change the principle against compelled speech.