Why might this fact make changing society difficult?

since most of current immigration into the u.s., both legal and illegal, is coming from latin america. it would be very difficult to imagine or rationalize a country my fellow citizens are trying desperately to flee into, would pose a threat to my prosperity or freedom. since the u.s. has a long history of intervention, but no record of permanent occupation, i would not feel oppression is the main objective.  

the largest free trade nation, along with the largest gdp in the world wanting to expand it's economic policy on us, and including us, could only be positive. the u.s. government has no interest in, or way of simply forcing american culture on us. and has no track record of it. other nations that adopted american social culture, or "americanization" did so voluntarily, mainly through the choice of allowing american businesses and u.s. citizens to come into their nations, as free operatives.

by improved communication.

newly independent countries of the former ussr

the first 10 amendments to the u.s. constitution are known as the bill of rights. those 10 amendments establish the most basic freedoms for americans including the rights to worship how they want, speak how they want, and assembly and peaceably protest their government how they want. the amendments have also been subject to much interpretation since their adoption, particularly the right to carry a gun under the second amendment.

"a bill of rights is what the people are entitled to against every government on earth, general or particular, and what no just government should refuse, or rest on inference," said thomas jefferson, the author of the declaration of independence and the third president of the united states.