Public opinion favors regulatory standards in trade agreements

The result of polling people in seventeen countries:

Strong majorities in developing nations around the world support requiring countries that sign trade agreements to meet minimum labor and environmental standards, a multinational poll finds. Nine in 10 Americans also support such protections.

If domestic constituents support labor and environmental regulations, why do they need to be tied to trade agreements?

Possible answers:

(1) Domestic constituents favor legislating these standards independent of trade agreements, but the survey didn’t ask the question in that form. Poor country policy makers aren’t responsive to their constituents’ opinion on this issue, in trade talks or otherwise.

(2) The meaning of the phrase “minimum standards” differs across users. Poor country governments reject strict standards designed to protect rich country proponents, but they would favor standards better tailored to their circumstances.

(3) Developing country citizens feel that international commerce differs in important ways from domestic economic activity and therefore should be conducted under different rules.

Other hypotheses?