The parallel is pure, Danno. Pelosi embargoed the text of Obamacare exactly as the text of these trade agreements was embargoed.
When it is really crooked, the power elites abhor transparency and will not give the public a chance to affect the outcome. As Peter R said, the other EU politicians will not follow Cameron's "mistake" in allowing referenda.
As Fast Eddie said "trade will find a way." Yes, but I would add - but at a cost. Interest groups buy protection from the politicians in the form of tariffs, or whatever barrier or Warren Buffett "moat" they pay for. Then, competitors, often called "smugglers" or some other pejorative, find a way. There is a cost but that cost is less than the spread, so smuggling remains profitable.
As an aside, the second President of the U.S., John Adams, before the Revolutionary War was a smuggler. He smuggled tea from Ceylon and the Danes to evade King George's tariff on tea. At the Boston Tea party, the "Indians" who threw the British Tea into the harbor were working for/with John Adams. The twist to that story is generally not taught. The reason the tea smugglers threw that tea into the harbor is that King George, in response to protests over the Stamp Act and other tariffs, had CUT the tariff on tea ! That cut was so great that Adams and his fellow smugglers were caught out with tea that they had paid too much for! They had to destroy that British tea in order to be able to sell theirs.
It is only in the very modern world that policy makers have imagined that borders and citizenship are archaic and useless impediments to trade. They have forgotten about the "free rider" problem. Throughout the history of trade, borders and citizenship were a way to force everyone who enjoyed the benefits of government - defense, courts, contract enforcement, property rights, common infrastructure/walls/gates/wells/irrigation - to pay for those benefits. Suppose some stranger walks into town, is he supposed to enjoy what everyone else has previously paid for? No, not so fast. Pay up. Pay a head tax, pay a tariff on the load of grain you brought in, and so on. Of course, this was not always so democratic, it was also, and mainly, just some strong man and his family and his thugs, who set themselves up as royalty, and who threw bones to their bishops and priests to make up stuff like the "divine right of kings" and so on. The point is that that list of the benefits of government is what enabled large scale trade - made it possible for producers: to plant, to build, to manufacture, to specialize. Production precedes sale. And borders and citizenship are critical components.