One word: corruption.
That's a pretty broad list, spanning several major industries, and includes some of the top companies in the country.
To answer a question of why this is still going forward despite some vocal opposition with "corruption" is very lazy thinking.
Wait, nevermind. I forgot that giving government officials money is free speech now. Carry on. ;)
What makes you think they have influenced democratically elected governments "specifically without the people"? In the US, 49% think it is a good thing, and 29% think it is a bad thing [1]. In most of the other countries involved, support is higher (see same link).
> Wait, wait, hold the phone. I forgot that giving government officials money is free speech now. Carry on.
Spending on TPP is greatly exaggerated [2].
[1] http://www.pewresearch.org/fact-tank/2015/06/23/americans-fa...