The main difference between Finland's education system and ours is that Finland has stricter criteria for teachers with regards to their education (I believe it's a Master's degree in their chosen subject for a permanent job). In exchange, teachers are compensated far better (part of the reason is that there are fewer teachers in the system), have more say in how educational reform is achieved, and are granted considerable autonomy in the classroom (aside from teaching the core curriculum). Management is also top-notch.
Finland also provides free and mandatory public education, paid entirely by the government (rather than having teachers pay for school supplies). The government has also placed a high priority on education and there is political consensus on this issue.
This is obviously the key problem in implementation of a Finland-like system in the United States: A substantial portion of the population don't really want to add additional financial burdens on the government, trust our government (or our teachers and school administrative staff for that matter) on matters related to education, or provide the federal government with more say in our children's education. We also don't really have a political consensus on the matter of education; we can't even agree on whether or not creationism should be taught in schools (please don't take up this line of argument, I'm just using it as an example), let alone how to reform our system.
I would agree. I recently read an essay by child psychologist David Elkind that the reason why most reforms fail in America (specifically the reform for a constructivist based approach) is because they lack at least one of three critrea: teachers, curriculum, and society. Basically we need a standard for the teaching profession which agrees on how things should be done. However in the US we have at least 51 different standards regarding teacher qualifications, and there are so many pedagogical schools that forming a consensus on how to approach the classroom would be near impossible. How can you plan to implement constructivism in the classroom when a vast number of teachers are angrily opposed to that type of instruction, or haven't been trained at all to implement it? Then you have problems of curriculum in which you have to establish just what students learn, how, and in what order. This has an even greater multitude of differing opinions. Finally you need society to agree on the reform and put their political, financial, and psychological support behind the effort. For example, as you mentioned, how can you adequately teach a subject like evolution if society itself is divided on the issue?
Ultimately I feel Elklind lays out the same argument you made. In Finland it appears the teachers, curriculum, and society all work in concert, while here in the US we have hundreds of different approaches each at odds with each other on the social, curriculum, and social levels.