n0, thanks for the questions. My original claim was fairly limited to what is written in responsa. The fact that there are less questions about some subject does not change the halakha, it just reduces amount of new material on the subject and makes that area of halakha less popular and less relevant to the changing times. If you are forced to decide whether it is ok to hide your income from IRS using medieval sources only, it will be a difficult and error-prone process.
but to your larger, interesting, point. I found an interesting paper
THE DEMOCRATIC EVOLUTION OF HALAKHAH:
A Political Science Perspective by David Raab from Touro College
here are some quotes – but read the original, it has a lot of thoughts and sources,
you asked about R Soloveichik
.. dispute over whether there is a positive commandment to appoint a king. R. Joseph B. Soloveitchik said in the name of his father that even if there is such a commandment, the commandment is dependent on the vox populi. The people must make its voice heard, as was the case in the time of Samuel, and only when a demand emanates from the people does the commandment apply
…
The individual—particularly if not affiliated with a particular
community, but even if so—may designate any decisor of his choosing.
He is required to select a rabbi with whom he can “meaningfully
identify” with a “principled and consistent attachment,” someone who
speaks to one’s own inner sanctum, to serve as an ongoing decisor.73 One
is not permitted to hopscotch from one decisor to the next to find the
most preferred specific ruling.74 Nor is one permitted to ignore one’s
decisor’s ruling, once asked for and received. However, the binding to a
decisor need not be permanent: a person may switch decisors The elasticity in selecting one’s rabbi is at the core of halakhic
democracy. For, those endowed with halakhic rule-crafting authority—
the rabbis—are selected or appointed, directly or indirectly, by the
people. While control over halakhic decision-making is vested in the
rabbis, they may be replaced relatively freely if desired.
over the
course of his lifetime if he no longer wishes to adhere to the philosophy
or rulings of his current one.75 Similarly, an individual may seek the
guidance of a different “specialist” decisor in areas where he feels that
his chosen decisor has less proficiency than needed in the matter at
hand.
As R. Judah Patriarch (Rebbi) was dying, he instructed his son, R. Gamliel, to appoint
Hami b. R. Haninah as head of the yeshiva. The Talmud asks, “And why
did Rebbi himself not appoint him?” R. Drosa responds: because the
people of Sepphoris protested. JT Ta’anit 4:2 20b.
The rishon Rivash (R. Yitzhak b. Sheshet, 1326-1408, Spain) ruled that a person may not request authority over a community from the king without the concurrence of the community
aharon Rema agrees, and both add that whoever does so “causes pain
to the public and will end up having to answer for it.”91 The Sephardic
aharon R. Eliyahu Mizrahi (d. 1525, Turkey) writes that the authority
given “to each Court in each generation…is due only to the fact that the
great court of each generation, all the people of that generation rely on
[that court’s] opinions.”
First-century tanna R. Eleazar b. Tzaddok ruled that any gezeirah
enacted by a court but not accepted by the majority of the people is no
gezeirah.JT Avodah Zarah 2:8, 16a (2:9, 41d); JT Shabbat 1:4 10b.
R. Meir decreed that kuthim (now often referred to as the Samaritans) were considered
complete idolaters and were thus to be shunned, but the people did not
accept his ruling.BT Hullin 6a.
Klei Hemdah (R. Meir Dan Plotzky, 1866-1928, Poland),
Ha’azinu, pp. 336-338 regarding the conflict between obedience to rabbinic law versus
the people’s ability to flout specific rulings.