Because labor is a technology, "workers," as such, are not a class and have no political interests. The important distinction is not between labor and capital; it is between contributing something a machine cannot contribute more cheaply and not so contributing, between bargaining to be paid out of the first dollars of revenue and bargaining to be paid out of the last dollars of revenue. Entrepreneurship is socially useful labor, and, I submit, it will be the last activity that will cease to be "socially necessary labor," right before the machines take over.
To put it another way, the only "Socially Necessary Labor" is activity (including thought) that cannot be done more cheaply by a machine. When there were many things that could only be done most cheaply by a human with the ability to do a repetitive task, all organized work was socially necessary labor. But even then, the value of the resulting commodity arose from organizing that work, not from the work. Some of that organizing was done by the worker - such organization is called "skill - and some was done by managers who organized the skilled workers. But management is no more or less SNL than carpentry. Ditto hiring managers and marketing products and deciding to what enterprises capital - payment for labor whose social necessity is not yet clear - is to be allocated.
The big theoretic hole in the LTV is that it assumes that SNL exists ex ante, when in fact it is discovered ex post to have been done. If I invest in a Concrete Life Preserver factory, it is because I believe that the production of CLPs will entail SNL. If I am wrong, then that labor is not SNL, which is proven by the fact that my CLPs have no value. OTOH, if I invest in life preservers that actually save lives, my business may prosper, and the activity that goes into making them will have proven to be SNL. Thus, the commodity does not get its value from the SNL; the activity becomes SNL because the commodity has value. Quantifying that SNL as some indicium of value is just silly.