The problem with "streamlining business practices" is that it turns into "common regulatory schemes." With big business the only "stakeholder" at the table, you can bet that regulatory hurdles will be set up that preclude competition from smaller business, usually by means that require economies of scale in the paperwork business (IOW inefficiency). With common regulatory schemes the benefits of federalism vanish and natural law competition among regulatory entities disappears as well. Thus there are no checks and balances to corruption being the engine for how applicable choices are made.
It's stupid, unless you are a monopolist interested in buying favors from unaccountable bureaucrats.
Free trade agreements carry an inherent imperative toward regulating and harmonizing more and more activities within each of the countries party thereto.
In their quest for successively ever more level playing fields, there is a natural tendency for free traders to inevitably seek to harmonize not just explicit tariff rates, but tax systems, labor laws, environmental regulations and any other differences in internal law that tends to confer an advantage on businesses in one jurisdiction over those of another.
We have seen this in the EU, as it has advanced progressively over the years from a coal and steel union centured on the Ruhr to a European-wide federal government, and the forces that produced NAFTA are pushing in the same direction, though we are at a much earlier stage of the process.