The WTO is a creation of governments and ultimately under their control. If the US wanted to change how medical patents work it could absolutely do so. These are government failings and blaming them mostly or exclusively on private companies is ridiculous.
Well yeah, but not all governments are equal. Sure, if the USA wanted to it could do whatever it wanted to, but that’s not the case for any other country in the world.
And the same people that wrote those legislation are also the ones running big pharma.